010 Chemistry 1st term : Give reason, what meant by,
What is meant by : Pipette
A glass tube with two openings which used to measure and transfer a certain volume of liquids
What is meant by : substances are completely ionized in their solutions
A glass tube with two openings which used to measure and transfer a certain volume of liquids
What is meant by : Symbolic chemical equation
A group of chemical symbols and formulas of the reactants and products
What is meant by : Burette
A long glass tube with two openings its graduation starts from top to bottom
What is meant by : The ions which are surrounded by water molecules in aqeous solutions of salts
A long glass tube with two openings its graduation starts from top to bottom
What is meant by : nanometer
A measuring unit that equals one part per billion from the meter
What is meant by : The acidic radical of the salt
Anion
What is meant by : What is meant by : Equal volumes of different gases at constant temperature and pressure contain an equal number of molecules
Avogadro's postulate
Calculate the number of carbon atoms in 50 g of calcium carbonate
CaCO3 (40 + 12 + (3x16) = 100 g , 50 g -------> C (6.02 x 10^23 atoms) , number of atoms of carbon = 50 x 6.02 x 1023/100 = 3..01 x 10^23 atoms
Give reason for : in the following reaction : H+ + F- ----> HF , H+ ion acts as an acid and F- ion acts as a base, according to lewis's theory
Because H+ accepts an electron pair while F- donates an electron pair
Give reason for : The pH value of the aqueous solution of sodium carbonate is higher than 7
Because NA2CO3 is produced from the reaction between a strong base and a weak acid So its pH value > 7
Give reason for : Chemistry contributes in increasing the production of crops and getting rid of agricultural pests
Because chemistry can prepare the suitable fertilizers for each crop and produce the insecticides
Give reason for : blood is considered as a colloid
Because chemistry can prepare the suitable fertilizers for each crop and produce the insecticides
Give reason for : We can distinguish between the suspension and colloid by the naked eye
Because colloid can't be seen by naked eye while suspension can be seen by the naked eye
Give reason for : The boiling point of NaCl solution is equal to the boiling point of KNO3 solution
Because each of them produces the same number of moles of ions in the solution
Give reason for : FeCL3 is named iron (III) chloride while AICL3 is aluminum chloride although the valence of iron and aluminum is 3 in the two salts
Because iron has two valences (II, III) while aluminum has only one valence (III)
Give reason for : Ammonia is considered as a base although it doesn't contain hydroxide group
Because it dissolves in water giving an aqueous basic solution
Give reason for : According to the bronsted-Lowry's theory water acts as an acid when it reacts with ammonia gas and as a base when it reacts with hydrogen chloride gas
Because it gives up a proton to ammonia molecules while reaction with it while it accepts the proton while reacting with hydrogen chloride
Give reason for : measurement has an important role in chemistry
Because it gives us information about the type and the concentration of elements forming the substance, monitoring and health protection and Diagnosis and suggesting the suitable medication in case of defects
Give reason for : water is polar solvent
Because it gives us information about the type and the concentration of elements forming the substance, monitoring and health protection and Diagnosis and suggesting the suitable medication in case of defects
Give reason for : When adding phenolphthalein indicator to sodium carbonate solution it turns into pink color
Because it is a base and the pH > 7
Give reason for : Nitric acid is a good conductor of electricity
Because it is considered a strong base
Give reason for : The empirical formula doesn't represent the actual composition of a compound
Because it is just an integer numerical ratio of the atoms or ions
Give reason for : Chemistry plays an important role in medicine and pharmacy
Because it is used to let us know the nature of functions of the hormones and enzymes and explaining the role of medicine inside the body
Give reason for : The mixture of table salt in water is a solyution while the mixture of table salt in kerosene is a suspension
Because it is used to let us know the nature of functions of the hormones and enzymes and explaining the role of medicine inside the body
Give reason for : Flasks and beakers are made of pyrex glass
Because it resists heat, so they do not break with heating or by the heat of the chemical reactions
Give reason for : hydrochloric acid is a strong electrolyte in aqueous solutions ions are not found in their single form
Because it resists heat, so they do not break with heating or by the heat of the chemical reactions
Give reason for : Phenolphthalein can't be used to differentiate between acidic and neutral media
Because it turns colorless in netural medium and acidic medium so u can't determine the solution
Give reason for : Sodium carbonate is a base
Because its molecular structure is a base
Why can't a round bottom flask be used during titration
Because its rounded bottom prevents its settlement on the base of the stand
Give reason for : There is no colloid of a gas-gas type
Because mixed gases are homogeneous mixtures whereasthe colloid is a heterogeneous mixture
Give reason for : Measuring the pH value is very important in chemical and biochemical reactions
Because pH value determines if the solution is acidic, basic or neutral
Give reason for : in a mixture of 20 mL of ethyl alcohol and 100 ml of benzene the alcohol is the solute
Because pH value determines if the solution is acidic, basic or neutral
Give reason for : The pH-meter is more accurate than the pH test paper tape to determine the pH value of the solution
Because ph value appears on its screen
Give reason for : the aqueous solution of sugar is a non electrolyte
Because ph value appears on its screen
two types of gold rings, rings (A) are red, while ring (B) is golden, what is the scientific explanation of the red colour of the rings (A)?
Because rings (A) are made of gold nano particles whose ratio between surface area and volume is very large this turns their colour from golden into red
Give reason for : The ionic equation Nacl ---> Na + Cl represents dissolving process at melting process
Because sodium chloride disolves in water and produces a Hydrated sodium ion and a Hydrated chloride ion
Give reason for : Sulphuric acid has two types of salts
Because sulphate has sulphate anion and bisulphate anion
Why is the molecular model of bucky ball eligible for storing hydrogen
Because the cavity of bucky ball allows the storing of a hydrogen gas
Give reason for : Naming the empirical formula by this name
Because the empirical formula can be calculated by knowing its molecular formula
Give reason for : The boiling point of sodium carbonate solution is higher than the boiling point of sodium chloride solution with the same concentration
Because the number of moles of ions dissolved in the solution of Na2CO3 is higher than that in the solution of NaCl and the boiling point increases by increasing the number of moles of ions dissolved in the solution
Give reason for : The vapor of a solution is lower than the vapor pressure of its pure solvent
Because the number of solvent surface molecules in solution is less than that in the pure solvent as the attraction forces between solvent and solute molecules in the solution is stronger than the attraction forces between the solvent molecules with each other
the reason of the different tase of tahini from the taste of sesame of which it is made
Because the ratio between (surface area : volume) in tahini is much larger than in the used sesame seeds
Why do silver nano particles have unique properties compared with silver micro particles
Because the ratio between their (surface area : volume) is very large
Give reason for : The boilingg point of a solution is higher than that of its pure solvent
Because the vapor pressure of solution is lower than the vapor pressure of pure solvent which forms it
Give reason for : Acetylene gas and aromatic benzene have the same empirical formula but they are different in their molecularr formula
Because their molecular masses are different
Give reason for : Some salts are prepared by the reacion of acids with metal oxides and not with metals directly
Because there might be a difficulty when the acid tries to react with the metal directly
Give reason for : The presence of a pipette supported with a sucking tool is important to be in the chemical laboratory
Because these are used with very hazardous materials
Give reason for : the aqueous solution of sugar is a non electrolyte
Because these are used with very hazardous materials
Give reason for : One litre of any gas contains the same number of molecules at STP
Because they all have the same volume
Give reason for : All neutralization reactions have the same ionic equation
Because they all produce water
Give reason for : oil doesn't dissolve in water but dissolves in benzene
Because they all produce water
Give reason for : Both of citric acid and phosphoric acid have the same degree of basicity while they differ in their sources
Because they are both weak acids
Give reason for : The empirical and molecular formulas off methane gas are identical
Because they are similar in their structure
Give reason for : The color of indicator changes according to the type of solution
Because they are weak organic acids/bases
Give reason for : The reaction of carbonate or bicarbonate salts with some acids is called acidity test
Because this reaction is used to detect the presence of acids as a strong effervescence occurs and CO2 gas evolves which turns the clear limewater into turbid
Give reason for : The pH value of ammonium chloride solution is less than 7
Because this solution is acidic where NH4Cl is produced from the reaction between a strong acid and a weak base
Give reason for : The pH value of the aqueous solution of ammonium acetate is equal 7
Because this solution is neutral where CH3COONH4 is produced from the reaction between a weak acid and a weak base
Give reason for : Phenolphthalein can't be used to differentiate between water and ammonium chloride solution
Because water is a neutral and ammonium chloride is a base so they both will give a pink color
Give reason for : HNO3 is an arrhenius acid whereas Mg(OH)2 is an Arrhenius base
Because when HNO3 is dissolved in water it gives hydrogen ions while Mg(OH)2 gives negative hydroxide ions
What is the science which is interested in studying locust egg laying
Biology
What is meant by : Nanochemistry
It is one of the nano science branches which deals with the chemical applications of nano substances
What is meant by : The ability of an atom to attract the electrons of the chemical bond towards itself
It is one of the nano science branches which deals with the chemical applications of nano substances
What is meant by : the solution in which the solvent contains the maximum amount of solute at a ertain temperature
It is one of the nano science branches which deals with the chemical applications of nano substances
What is meant by : The number of moles of solute dissolved in one kilogram of solvent
Molality
What are the nanosuits that can be used for this purpose
Nano shell
there is 2 glass beakers : - First : is filled until the mark of 100 mL with 180 g of sugar, Second : is filled until the mark of 100 mL with 100 g of water
The mass of the mixture = 180 + 100 = 280 g, The volume would be a little less than 200 mL / Because some sugar molecules will fill the intermolecular spaces between water molecules
What is meant by : A phenomenon used to distinguish between the colloid and the true solution
Tendal's phenomenon
Give reason for : Salt is added to snow-covered roads in cold places
To prevent cars from slipping and decrease the number of accidents where salt dissolves in water forming a solution which freezes at a temperature below the freezing point of pure water
What is meant by : Ionic equation
The chemical equation in which some or all reactants and products are written In the form of ions
Give reason for : scientists inspired to use carbon nano tubes to produce space shuttles
because a nano tubes which have the size of a human hair can easily pull a truck
Give reason for : Acid and base are correlative to each other, according to bronsted-lowry's theory
because acids gives up protons while bases accept protons
Give reason for : The equal masses of different elements don't contain the same number of atoms
because atoms of the same chemical element do not always have the same mass
Give reason for : Hydrochloric acid is a strong acid while acetic acid is a weak acid
because hydrochloric acid is completely ionized in water while acetic acid is incompletely ionized in water
Give reason for : The molar mass of phosphorus depends on its physical state
because it can change if it is a liquid gas or solid
Give reason for : The arrhenius's theory is deficient
because it cannot define all types of acids and bases
Give reason for : the bucky ball is denoted by c60
because it consists of 60 carbon atoms
Give reason for : ammonia isn't considered to be a base according to arrhenius's theory, but considered to be in bronsted-lowry's theory
because it doesn't contain a source of (OH-) ions in arrhenius theory while in bronsted-lowry's theory ammonia accepts a proton from another substance during the reaction
Give reason for : The mixture of a chalk's powder in water is a suspension
because it is a heterogeneous mixture
Give reason for : The colloid is an intermediate between the solution and the suspension
because its size of particles ranges between 1:1000
Give reason for : Acetic acid is a monobasic acid while phosphoric acid is a tribasic acid
because nitric acid contains 1 hydrogen atom while phosphoric acid contains 3 hydrogen atoms
Give reason for : Not all bases are alkalis
because not all of them dissolves in water and gives hydroxide ion
Give reason for : one litre of O2 gas contains the same number of molecules of 1 litre of Cl2 gas at STP
because number of molecules is equal to number of moles x avogadro's number
Give reason for : The mass of one mole of oxygen molecules is double the mass of one mole of oxygen atoms
because oxygen molecules have 2 oxygen atoms combined
Give reason for : Nano is considered a unique scale
because substances gain unique properties in the nano scale differ from their properties in macro ro micro scales
Give reason for : A mixture of sugar in water is a solution while a mixture of milk powder in water is a colloid
because sugar is a homogeneous while milk powder is a heterogeneous
Give reason for : powdered sugar dissolves in water faster than a block cube at the same temperature
because sugar powder has a greater ratio between the surface area and the volume than that of a sugar cube
Give reason for : The freezing point of a solution is lower than that of its pure solvent
because the attraction forces between the solvent molecules and the solute molecules in the solution hinders the conversion of the solvent from liquid state to solid state hence it is required to decrease the temperature of the solution to less than the freezing point of the pure solvent
Give reason for : the color of gold changes when the dimensions of its particles change from macro scale to nano scale
because the reaction of gold particles in nano scale with light differs from its reaction with light in macro scale
Give reason for : The volume of gas at STP can be calculated in terms of the molar mass and should be placed in the standard conditions of pressure and temperature
because the volume of gas = number of moles of gas x 22.4
Give reason for : carbon nano tubes can be used as a biological sensor devices
because they are connected easily to protein
Give reason for : 28 g of nitrogen gas occupy the same volume of 2 g of hydrogen gas
because they have same number of molecules according to avogadro's postulate
Give reason for : The volume of 26 g of acetylene gas (C2H2) is equal to the volume of 2 g of H2 gas at STP
because they have same number of molecules according to avogadro's postulate
Which is higher the melting point of silver particles in micro scale or nano scale
in nano scale the melting point of silver particles is lower than those in micro scale
What is meant by : Chemical substances their colors change with the change of the type of solution
indicators
What is meant by : one dimensial nano substances
nano substances are used in painting surfaces and packaging food products
What is meant by : Measurement
the comparison of an unkown quantity with another quantity of the same kind in order to know the number of times which the first includes the second
What is meant by : a covalent bond formed between two atoms which are different in electronegativity
the comparison of an unkown quantity with another quantity of the same kind in order to know the number of times which the first includes the second
What is meant by : the solution which can be obtained from the saturated solution by heating and adding an excess mamount of solute to it
the comparison of an unkown quantity with another quantity of the same kind in order to know the number of times which the first includes the second
What is meant by : Bases that are partially ionized in water
weak bases
In which of these two samples sulphur mass is larger : - 35 g of sodium sulphite Na2SO3 - 40.8 g of calcium sulphate CaSO4
(1) Na2SO3 (2X23) + 32 + (3x16) = 126 g 35 g ----------> S (32g) , Mass of sulphur = 35 x 32/126 = 8.89 g, (2) CaSO4 (40 + 32 + (4x16) = 136g 40.8g -------> S (32g) , Mass of sulphur = 40.8 x 32/136 = 9.6 g ; CaSO4 sample contaains laaarager mass of sulphur
Chemical analysis of the substance Xcl2 revealed that 0.25 mol of it has a mass = 100 g Calculate the number of moles of X2 ions and chloride ions which is present in 200 g of this substance
0.25 mol of XCL2 ----------> 100 g, 200 g ; Number of moles of XCL2 = 200 x 0.25/100 = 0.5 mol ; XCL2 ------> X2 + 2CL , Number of moles of X2 = 0.5 mol, number of moles of Cl- = 1 mol
Calculate the mass of 100 atoms of copper
1 mol (cu) (63.55g) -----------> avogadro's number of atoms (6.02 x 10^23, 100 atoms) Mass of 100 atoms of copper = 100 x 63.55/6.02 x 1023 = 1.056 x 10-20 g
The bottle which is shown in the opposite figure contains 100 tablets where each tablet contains 0.076 g of iron (II) sulphate FeSO4these tablets are used to treat iron deficiency
1 tablet -----> FeSO4(0.076g) , Mass of FeSO4 = 100x0.076/1 = 7.6 g , FeSO4 (55.8 + 32 + (4x16) = 151.8g, 7.6g) ----> Fe(55.8g) ; Mass of Fe = 7.6x55.8/151.8
Calculate the number of oxygen molecules which are required to form 72 g of water vapour on the reaction with excess of hydrogen
2H2 + O2 ------------> 2H2O , Molar mass of H2O = (1x2) + 16 = 18 g/mol , O2 (6.02 x 10^23) -----------> 2H2O ((2x18) = 36 g, 72 g) Number of O2 molecules = 72 x 6.02 x 10^21/36 = 1.204 x 10^24 molecules
Two atoms of Rubidium Rb combine with one atom of oxygen O to form rubidium oxide Calculate the mass of rubidium oxide which is produced from the reaction of 1.98 g of rubidium with excess of oxygen
2Rb + 1/2O2------------> Rb2O ; 2Rb (2x85.5) = 171 g, 1.98 g -------> Rb2O ((2x85.5) + 16) = 187 g Mass of rubidium oxide = 1.98 x 187/171 = 2.17 g
Calculate the mass of bromide ions which are present in a mixture of 2 mol of XBr compound with 3 mol of YBr2 compound
2XBr ----> 2x + 2bR ; 3YBr2 -----> 3Y2 + 6Br / 2XBr + 36Br2 ----> 2X + 3Y2 + 8Br , Mass of bromide ions BR- = Number of moles x molar mass = 8 x 79.9 = 639.2 g
A doctor has prescribed 0.125 g of ampicillin for a patient if each 5 mL of the ampicillin syrup medication contains 250 mg of ampicillin, calculate the volume which is required for the patient
5 mL syrup ----> 250 mg ampicillin, the volume required = 2.5 mL
What is meant by : suitable measuring unit
A certain portion of a certain physical amount and used as an indicator to measure an actual portion for this amount
What is meant by : the molecules that have an end carrying a partial positive charge and another end carrying a partial negative charge
A certain portion of a certain physical amount and used as an indicator to measure an actual portion for this amount
What is meant by : the solution which can be obtained when you put a crystal of solute in its supersaturated solution
A certain portion of a certain physical amount and used as an indicator to measure an actual portion for this amount
What is meant by : Volumetric flask
A flask used to prepare solutions with very accurate known concentrations
What is meant by : the solution which accepts more amount of solute at a certain temperature
A flask used to prepare solutions with very accurate known concentrations
What is meant by : Graduated cylinders
A glass container used to determine the volume of irregular solid bodies
What is meant by : the substances in which their solutions or moltens don't conduct electric current as there are no free ions
A glass container used to determine the volume of irregular solid bodies
What is meant by : Three dimensional nano substances
A nanotechnology used to remove blood clots from the vein walls without surgical interference
What is meant by : Nanochemistry
A science deals with studying describing and preparing the substance with nano dimensions
What is meant by : A substance that dissolves in water to give positive hydrogen ions H+
Arrhenius acid
What is meant by : A substance that dissolves in water to give negative hydroxide ions OH-
Arrhenius base
What is the type of this soil? Explain (if the device used to measure the acidity of the soil chose for ph)
Acidic soil / as its pH value = 4
What is meant by : The quantity of products that is actually produced from the chemical reaction
Actual yield
What is meant by : The sensitive balance
An apparatus used to measure the masses of substances
What is meant by : the substances in which their solutions are moltens can conduct electric current by the free ions movement
An apparatus used to measure the masses of substances
What is meant by : What is meant by : A constant number represents the number of particles in onemole of substance
Avagardo's Number
What is meant by : What is meant by : The volume of one mole of any gas at STP
Avogadro's law
What is the importance of the presence of this label on the nutritional product
Awareness of the quality and the quantity of the componenets especially for the persons who are on certain diets
When the volumes are equal which is lighter diamon or carbon nano tubes
Carbon nano tubes
What is meant by : The substance that gives up the proton H+
Bronstad-lawry acid
What is meant by : The substance that has the ability to accept the proton
Bronstad-lawry base
If u have a metal base stand, What is the tool which is held by the champ of this stand? And what is the tool which is put on the base during titration
Burette is held by the clamp of the stand and a conical flask is put on the base
Allotropy is a chemical term which means the existence of one element in several different crystalline forms which are similar in their chemical composition diamond and graphite are two old allotropes of carbon, mention three allotropic forms that are considered new forms of carbon
Carbon nano tubes carbon nano wires, bucky ball C60
What is meant by : The basic radical of the salt
Cation
What is meant by : Medicines
Chemical compounds that have healing properties and can be extracted from natural sources or prepared in laboratories
What is meant by : The substance that exists in the largest amount within the solution
Chemical compounds that have healing properties and can be extracted from natural sources or prepared in laboratories
What is meant by : A heterogeneous mixture in which the diameter of its particles ranges between 1:1000 nm
Colloid
the movement of the ions with or against the gravity of earth through a root hair of a plant, Suggest the names of the sciences that are likely to be combined in this kind of studies
Combination between chemistry, physics and biology
What is meant by : The substance that is produced when a base accepts a proton
Conjugate acid
What is meant by : The substance that is produces when an acid loses a proton
Conjugate base
What is meant by : A method used for preparation of colloids by crushing the substance into small particles then added to the dispersed medium with stirring
Dispersion method
Give reason for : The practical yield is less than the theoretical yield
Due to - Reactants may contain impurities, - volatilizaton of a part of the products during the reaction
Give reason for : The formation of red precipitate when adding drops of potassium chromate solution to silver nitrate solution
Due to formation of silver chromate compound
Give reason for : sugar sdissolves in water although it is a non polar compound
Due to formation of silver chromate compound
Give reason for : the effectiveness of using the bucky ball as a carrier for medicine
Due to its hollow structure it can be fitted with the molecules of medicine and protects it from the reaction with certain molecules inside the body
Give reason for : carbon nano tubes are stronger than steel
Due to the powerful bonds between its molecules
What is meant by : A symbolic chemical formula represents the simplest integer number ratio of the atoms of elements in a compound
Empirical formula
Environmental safety and health protection require considering some precautions during the spraying the land with the pesticide, suggest two fo these precautions
Ensuring that there is no animals in spraying area and Wearing protective eye wear during spraying to protect the eyes
What is meant by : A mixture that scatters the light beam and its particles can't be separated by filtration
Hetergeneous
Calculate the mass of potassium in a sample of potassium dichromatea K2CR2O7 its mass = 27.8 g
K2Cr2O7 (2x39) + (2x51) + (7x16) = 294 g 27.8 g ------->2K (2x39) = 78 g , Mass of potassium in the sample = 27.8 x 78/294 = 7.38 g
Calculate the mass of oxygen in 25.99 g of potassium chromate compound K2CrO4
K2CrO4 (2 x 39) + 51 (4 x 16) = 194 g 25.99 g ----->4O (4 x 16) = 64 g , Mass of oxygen = 25.99 x 64/194 = 8.574
What is meant by : The substance that accepts an electron pair or more
Lewis acid
What is meant by : The substance that donates an electron pair or more
Lewis base
What is meant by : The temperature at which the vapor pressure of the liquid equals the pressure exerted on it
Measured boiling point
What is the relation between the melting points of nano substances and their particles radii
Melting points of nano substances decrease with decreasing of their radii
What is meant by : Acids that usually have a non-metal elements in their composition
Mineral acid
Calculate the number of moles of ammonium ions in a sample of ammonium carbonate its mass = 22.5 g
Molar mass of (NH4)2CO3 = (2x14) + (8x1) + 12 + (3x16) = 96 g/mol ; number of moles of (NH4)2CO3 = mass of substance/molar mass of the substance = 22.5/96 = 0.234 mol ; (NH4)2CO3 -------> 2NH4 Number of moles of NH4 = 2 x 0.234 = 0.468 mol
Calculate the number of moles of the compound C3H8NO5P in a sample of it whose mass is 295.1 g
Molar mass of C3H8NO5P = (3 x 12) + (8 x 1) + 14 + (5 x 16) + 31 = 169 g/mol, number of moles of C3H8NO5P = mass of substanace/molar mass of the substance = 295.1/169 = 1.746
Calculate the molar mass of nitrobenzene compound C6H5NO2
Molar mass of C6H5NO2 = (6 x 12) + (5 x 1) + 14 + (2 x 16) = 123 g/mol
Calculate the mass of sodium carbonate which contains 1.773 x 10/17 carbon atoms
Molar mass of Na2CO3 = (2x23) + 12 + (3x16) = 106g/mol , Naa2CO3 (106g) ----> C (6.02 x 10^23 atoms, 1.773 x 10^17 atoms) Mass of sodium carbonate = 1.773 x 1017 x 106/6.02 x 1023 = 3.12 x 10-5 g
Calculate the mass of 6.761 mol of sodium hydroxide
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol, Mass of NAOH = Number of moles x molar mass = 6.761 x 40 = 270.44 g
Calculate the molar mass of lead element knowing that the mass of 0.2 mol of it equals 41.4 g
Molar mass of lead element = mass of lead/number of moles of leada = 41.4/0.2 = 207 g/mol
What is meant by : The number of moles of solute dissolved in one litre of solution
Molarity
What is meant by : A symbolic chemical formula represents the real number of atoms or ions in a molecules or the formula unit of a compound
Molecular formula
What is meant by : The salt which is produced from the reaction between a strong acid and a strong base
Neutralization point
What is meant by : The reaction between an acid and a base
Neutralization reaction
Calculate the number of the molecules of CO2 in 0.5 mol sample of it
Number of molecules = number of moles molecules x avogadro's number = 0.5 x 5.02 x 1023 = 3.01 x 1023 molecules
Calculate the length of the line which is formed from arranging the atoms of carbon which is present in 0.12 g of it knowing that the diamter of carbon atom = 0.7 nm
Number of moles of C atoms = mass/molar mass = 0.12/12 = 0.01 mol, Number of C atoms = Number of moles of atoms x Avogadro's number = 0.01 x 6.02 x 10^23 = 6.02 x 10^21 atoms, length of the line = Number of C atoms x diameter of C atom = 6.02 x 10^21 x 0.7 = 4.214 x 10^21 nm, Length of the line = 4.214 x 10^21 x 10^-9 = 4.214 x 10^12 m
What is the role of chemistry in protecting the harvests from the locust
Producing suitable intesticides
Mention the similarity and the difference between these three allotropes in terms of the number of carbon atoms that are bound to each other
Similarity between graphite and carbon nano tubes in that each carbon atom is bound with three other carbon atoms, the diamond is different where each carbon atom in diamond is bound to four other carbon atoms
What is meant by : The hetergenous mixture in which the diameter of its particles is larger than 1000 nm
Suspension
What is meant by : The number of protons (H+) produced from one molecule of the acid when it dissolves in water
The basicity of acid
What is meant by : A way of expressing the acidity and the alkalinity degree of solutions by numbers from (0 to 14)
The hydrogen exponent pH
What is meant by : The sum of masses of atoms in one molecule of inn element or a compound
The mole
What is meant by : What is meant by : The quantity of a substance that contains avogadro's number of atoms molecules or formula units
The mole
What is meant by : The temperature at which the vapor pressure of the liquid equals to the atmospheric pressure
The natural boiling point
Deduce a scientific probability of not smelling bad smells after using these socks for a whole day
The probability that silver nano particles have the properties of fkilling fungi and bacteria
What is meant by : Biology
The science that is interested in studying the living organisms
What is meant by : A homogeneous mixture of two substances or more
The science that is interested in studying the properties and structure of matter
What is meant by : Physical chemistry
The science that is interested in studying the properties and structure of matter
What is meant by : the number of grams of solute dissolves in 100 g of solvent to form a saturated solution at (Stp)
The science that is interested in studying the properties and structure of matter
What is meant by : Chemistry
The science that studies the composition and properties fo matter, the changes that occur on it, the reactions of different substances with each other and the suitable conditions of these reactions
What is meant by : Physics
The science which is interested in studying matter, its movement and energy
What is meant by : Biochemistry
The science which is interested in studying the chemical structure of the parts of the cell
What is meant by : The calculated quantity of products expected from given quantities of reactants
Theoretical yield
How can this soil be treated
Treated by adding a basic substance to it
What is meant by : The pressure that affects the liquid surface when the vapor is at dynamic equilibrium with the liquid inside a closed container at constant temperature and pressure
Vapor pressure
What is meant by : nanometer
a scale for measuring the very small particles is less than 100 nm
What is the future alternative of the steel rope which is characterized by the following properties : - it is much lighter than steel , - its diameter = 60000 nm
carbon nano wires
What is the indication of a label which is put on the bottle of HCL acid
it indicates that dealing with caution as it is corrosive
Deduce 2 phyiscal properties of CO gas
it is lighter ( has lower density) than water and insoluble in it
Calculate the number of oxygen atoms in 300 molecules of acetic acid CH3COOH
number of moles of acetic acid molecules = number of molecules/avogadro's number = 300/6.02 x 10^23 = 4.983 x 10^-22 mol , CH3COOH (4.983 x 10^-22 mol) -----------------> 2O , Number of moles of oxygen atoms = 2x4.983x10^-22/1 = 9.97 x 10^-22 mol , Number of oxygen atoms = Number of moles of oxygen atoms x Avogadro's number = 9.97 x 10^-22 x 6.02 x 10^23 = 600 atoms
What is meant by : The compound which is formed when an anion combines with a caution
salt
What is meant by : What is meant by : The reactant which is completely consumed in the reaction
the limiting reactant
What is meant by : volume dependent properties
the properties of nanoparticles which change with the change of its volume in nano scale
What is meant by : nano substances
the substances which their dimensions or one of them are less than 100 nm
What is meant by : nanotechnology
the technology that is interested in treating the substances in nano scale to produce resultants of new useful and unique properties
What is meant by : critical nano volume
the volume at which the unusual properties of the matter appear
