Chemistry 151 Chapters 1 and 2

What is the atomic mass of the element that consists of the following isotopes in the indicated natural abundances? Isotope Isotopic mass (amu) Relative abundance (%) 1 57.93 67.76 2 59.93 26.16 3 60.93 1.25 4 61.93 3.66 5 63.93 1.16

(57.93*.6776)+(59.93*.2616)+(60.93*.0125)+(61.93*.0366)+(63.93*.0116)= 58.7 amu

Based on your answer in Part A, calculate the number of atoms in this amount of 13C?

3.24×10^23 13C atoms

You are given a sample resembling silver. Which of the following properties could be used to help determine whether the sample is really silver?

-the melting point of the sample -the density of the sample

How many covalent bonds does hydrogen form if each of its unpaired electrons participate in one bond?

1 Hydrogen almost exclusively forms a single bond with other atoms, such as in H−H, NH3, H2O, or CH4.

4.3×10−6 is between which two numbers?

1*10^-5 and 1*10^-6

Common Cations

1+ Charge: H+, Li+, Na+, K+, Cs+ (cesium), Ag+ (Silver), NH4+ (ammonium) Cu+ (copper I) 2+ Charge: Mg+, Ca+, Sr+ (strontium), Ba+ (Barium), Zn+ (zinc), Cd+ (cadmium), Co+ (Cobalt II), Cu+ (Copper II), Fe+ (iron II), Mn+ (maganese II), Hg2+ (mercury I), Hg+ (mercury II), Ni+ (nickel), Pb+ (lead II), Sn+ (tin II) 3+ Charge: Al+ (aluminum), Cr+ (chromium III), Fe+ (Iron III)

Watch the animation depicting Rutherford's experiment and choose which of the following conclusions are correct. Check all that apply. 1. The mass of an atom is concentrated at the nucleus. 2. A positive charge is spread equally over the atom. 3. Positive charge is condensed in one location within the atom. 4. The majority of the space inside the atom is empty space. 5. The atom is a very compact entity without any empty space. 6. The atom contains a positively charged nucleus.

1,3,4,6

Convert the number 0.000127 to scientific notation, then enter the answer using a power of 10. You can select the button for scientific notation from the templates menu.

1.27×10−4

The fuel used in many disposable lighters is liquid butane, C4H10. How many carbon atoms are in 4.00 g of butane?

1.66×10^23 carbonatoms

How many covalent bonds does oxygen form if each of its unpaired electrons participate in one bond?

2 Oxygen mainly forms compounds with two bonds, such as H2O or CO2. However, like carbon, there are exceptions. In carbon monoxide, :C≡O:, oxygen contributes a lone pair to the triple bond, forming three bonds.

What is the ratio of hydrogen atoms (H) to oxygen atoms (O) in 2 L of water? Enter the simplest whole number ratio in order of hydrogen to oxygen, respectively.

2, 1

Phosphoric acid reacts with magnesium hydroxide to produce magnesium phosphate and water via the following reaction: ?H3PO4+?Mg(OH)2→?Mg3(PO4)2+?H2O Balance the equation, then enter the coefficients, in order, in the answer box.

2,3,1,6 he balanced equation is written as follows: 2H3PO4+3Mg(OH)2→Mg3(PO4)2+6H2O Notice that the equation shows a total of 12 hydrogen atoms, 2 phosphorus atoms, 3 magnesium atoms, and 14 oxygen atoms on each side.

2.03 g of C4H10 reacts with 7.28 g of O2 to form 6.16 g of CO2. Using only addition and subtraction, calculate the amount of H2O produced.

3.15g

The two isotopes of chlorine are 35/17Cl and 37/17Cl. Which isotope is the most abundant?

35/17 Cl Since the atomic mass of chlorine, 35.45 amu, is closer to 35 than it is to 37, 35Cl must be the most abundant isotope. 35Cl does in fact account for 75.53% of Earth's chlorine. The full calculation is (0.7553)(34.96885)+(0.2447)(36.96590)=35.45amu

How many covalent bonds does carbon form if each of its unpaired electrons participate in one bond?

4 While carbon mainly forms compounds with four bonds, such as CH4 or H2C=O, it does sometimes form compounds with fewer bonds, such as carbon monoxide. Carbon monoxide, however, has a lone pair on the carbon atom, :C≡O:. Two of the electrons from carbon are used to form the triple bond, and four from oxygen, however since the bond is shared equally the molecule is neutral.

Which of the following are equal to 5×10^10?

500* 10^8 0.5* 10^11 50* 10^9

How many atoms of hydrogen (H) are present in 200 molecules of ammonia (NH3)?

600 H Atoms

How many moles of atoms are in 7.00 g of 13C?

7/13 moles 0.538 mol 13C While the value of a mole is the number of atoms of 12C atoms in exactly 12.0 g of pure 12C, the same is not true for other elements or other isotopes of carbon. To six significant figures, the molar mass of 13C is 13.0034 g/mol. Significant Figures Feedback: Your answer 713 = 0.53846 mol 13C was either rounded differently or used a different number of significant figures than required for this part.

What is the chemical formula for sucrose?

C12H22O11

What is the formula for chlorous acid?

HClO2 (2 lower power)

Classify the following elements as halogens, alkali metals, alkaline earth metals, or noble gases.

Halogen: F, Cl Alkali metals: Rb, K Alkaline earth metals: Mg Noble gases: Ar

If the following elements were to form ions, they would attain the same number of electrons as which noble gas?

He: Li Ne: O, Mg Ar: Ca, P Kr: Rb, Br **The Li+ ion has 2 electrons, just like He. The ions Mg2+ and O2− each have 10 electrons like Ne. The P3− and Ca2+ each have 18 electrons like Ar. The ions Br− and Rb+ each have 36 electrons like Kr.

A solution of ammonia and water contains 4.60×1025 water molecules and 8.70×1024 ammonia molecules. How many total hydrogen atoms are in this solution?

How many H Atoms in H20: 9.20*10^25 How many H Atoms in Ammonia: 2.61*10^25 H Atoms = 1.18*10^26

Classify the following elements as main group elements, transition metals, or inner transition metals.

Main Group Elements: Ba, Pb, S Transition Metals: Ag, Zn Inner transition metals: U

Which of the following is not an element?

Water Elements are substances that cannot be broken down any further by chemical means. Water (H2O) is a compound that can be broken down into its elements, hydrogen and oxygen.

What is the systematic name of PbO?

lead(II) oxide

What is the systematic name of Mg(NO3)2?

magnesium nitrate

What is the name of the covalent compound N2O5?

dinitrogen pentaoxide

Give the balanced chemical equation (including phases) that describes the combustion of butene, C4H8(g). Indicate the phases using abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively.

C4H8(g)+6O2(g)→4CO2(g)+4H2O(g)

Which of following changes that affect the composition of our atmosphere involve physical changes and which involve chemical reactions?

Chemical Reaction: -oxygen gas changes to ozone during thunderstorms - carbon dioxide is produced by the combustion of gasoline in an automobile engine. - when coal, oil, and natural case are decomposed in landfills they produce methane gas. Physical Change: -freezing rain develops when a warm air mass overrides a cold air mass. -fog forms from water vapor when the temperature drops below the dew point

In a laboratory experiment, a fermenting aqueous solution of glucose and yeast produces carbon dioxide gas and ethanol. The solution was heated by burning natural gas in a Bunsen burner to distill the ethanol that formed in the flask. During the distillation, the ethanol evaporated and then condensed in the receiving flask. The flame of the burner was kept too close to the bottom of the flask and some of the glucose decomposed into a black carbon deposit on the inside of the flask. During this experiment the following changes occurred. Which of these changes involved a physical change and not a chemical change?

Evaporation of ethanol - condensation of ethanol

What is the chemical formula for potassium permanganate?

KMnO4 (4 to the lower power)

Part C What is the identity of element X from Part B?

The atomic mass of sulfur, 32.07 amu, is very close to 31.97207 amu because that is the isotope with the greatest percent abundance.

What is the mass percentage of each element in the compound Al2O3?

% Al,% O = 52.9,47.1 % Term 1: Significant Figures Feedback: Your answer 52.925 % was either rounded differently or used a different number of significant figures than required for this part. Term 2: Significant Figures Feedback: Your answer 47.075 % was either rounded differently or used a different number of significant figures than required for this part.

What is the atomic mass of a hypothetical element that consists of the following isotopes in the indicated natural abundances? Isotope Isotopic mass (amu) Relative abundance (%) 1 85.9 11.6 2 87.9 13.2 3 90.9 75.2

(85.9*.116)+87.9*.132)+(90.0*.752)= 89.9 amu sually the atomic mass of an element is closest to the isotope that makes up the majority of the natural abundance. In this example, isotope 3 had the largest relative abundance. Therefore the average atomic mass was closer to the mass of isotope 3 than to any of the other isotopes.

Based on the data Thomson collected in his experiments using cathode rays, the concept of atomic structure was modified. Which of the following statements about the atomic structure were validated by his cathode ray experiments?

- Cathode rays have mass -there are subatomic size particles in an atom -particles of the cathode rays are fundamental to all matter - matter contains negative charge and by inference positive charge. -(Cathode rays were later to become known as electrons—a term coined by another scientist, George Stoney. The "plum-pudding" model of the atom, with an atom as a sea of positive charge in which were embedded the negatively charged electrons, resulted from these initial experiments by Thomson.)

Based on the data gathered in the Rutherford's scattering experiments, the concept of atomic structure was modified. Which of the following aspects of the structure of the atom were validated by these experiments?

- The existence of the atomic nucleus - most of the atomic volume being empty -the charge of the nucleus being positive -the nuclear density being large

Based on the data gathered in Millikan's oil-drop experiments, the concept of atomic structure was modified. What aspects of the structure of the atom was validated by these experiments?

-Mass of an electron - charge on an electron

common anions

1- Charge: H- (hydride), F- (fluoride), Cl- (Chloride), Br- (bromide), I- (iodide), CN- (cyanide), OH- (hydroxide), CH3COO- (acetate), CIO3- (chlorate), CIO4- (perchlorate), NO3- ( Nitrate), MnO4- ( permanganate) 2- Charge: O- (oxide), O2- (peroxide), S- Sulfide, CO3- (Carbonate), CrO4- (chromate), Cr2O7- (dichromate), SO4- (sulfate) 3- Charge: N- (nitride), PO4- (phosphate)

Based on your answer in Part B, how many electrons are in this amount of 13C?

1.94×1024 electrons Significant Figures Feedback: Your answer 1.94400⋅1024 = 1.944×1024 electrons was either rounded differently or used a different number of significant figures than required for this part.

What is the formula mass of Mg(NO3)2?

148.3 g/mol

if a new element were discovered and it was found to form 1 -ions ,in which group would you place it in the periodic table

17 Elements in group 17 must gain an electron to have the same number of electrons as the adjacent noble gas. For example, F has 9 electrons, but it would be more stable if it had 10 electrons like Ne. Therefore, F will react to form a 1− ion (with 9 protons and 10 electrons).

Based on your answer in Part B, how many neutrons are in this amount of 13C?

2.27×10^24 neutrons Significant Figures Feedback: Your answer 2.268⋅1024 = 2.268×1024 neutrons was either rounded differently or used a different number of significant figures than required for this part.

A flask contains 0.390 mol of liquid bromine, Br2. Determine the number of bromine molecules present in the flask.

2.35×1023 molecules Significant Figures Feedback: Your answer 2.34858⋅1023 = 2.3486×1023 molecules was either rounded differently or used a different number of significant figures than required for this part.

Calculate the mass of 1.00×1024 (a septillion) molecules of water.

29.9 g Convert from # of molecules to mols, then from mols to grams. 1.00 x10^24/6.02x10^23 = 1.661 moles 1 mol of H2O weighs 18g 1.661 * 18 = 29.9 g

The figure (Figure 1) shows the reaction of element A (lavender spheres) with element B (tan spheres). Write the balanced chemical equation for this reaction in terms of A and B.

2A+3B2→2AB3 (2 and 3 are lower power) Balancing equations with polyatomic ions When balancing chemical equations with polyatomic ions, it may help to balance the ion as a whole. For example, the ion PO43− can be treated as a unit and balanced in both the reactants and the product, or you can break it down and balance each atom separatly.

Solid lithium metal and diatomic fluorine gas react spontaneously to form a solid product. Give the balanced chemical equation (including phases) that describes this reaction. Indicate the phases using abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively.

2Li(s)+F2(g)→2LiF(s)

Part complete Classify each reaction as an exchange reaction, a condensation reaction, or a cleavage reaction.

2NH4CL+Ba(NO3)2-->2NH4NO3+BaCl2 -- exchange ( --?-- ) HCl+NaOH---> NaCl+ H2O -- exchange (acid-base) Ca+2HCl---> CaCl+H2 -- exchange (redox) CaO+CO2--->CaCO3 -- condensation ( --?-- ) 2H2O-->2H2+O2 -- clevage (redox)

How many covalent bonds does nitrogen form if each of its unpaired electrons participate in one bond?

3 Nitrogen usually forms compounds by forming three bonds, such as in ammonia NH3. However, it too has exceptions. Nitric oxide, NO, may be drawn with a single double bond between the nitrogen and oxygen atom. In that Lewis structure, oxygen would have two lone pairs of electrons while nitrogen would have one lone pair and one additional single unbonded electron.

On the basis of Rutherford's experimental observations, which of the following statements describes the structure of the atom according to Rutherford's atomic model? 1. In an atom, all of the positive and negative charges are randomly distributed. 2. In an atom, positively charged particles are dispersed in the space surrounding the negatively charged sphere. 3. In an atom, the positive charges are located in a small core within the atom called the nucleus. 4. In an atom, negatively charged electrons are dispersed in the space surrounding the positively charged nucleus of an atom.

3, 4 -On the basis of his experiment, Rutherford proposed an atomic model. Postulates of his atomic model are as follows: An atom has a tiny, positively charged nucleus at its center. The positive charge is due to the presence of protons in the atom. Electrons are spread throughout the empty space around the nucleus of the atom. The number of electrons in an atom is equal to the number of protons in an atom, keeping the atom electrically neutral. The electrons and the nucleus are jointly held together by electrostatic forces of attraction.

You carefully weigh out 10.00 g of CaCO3 powder and add it to 40.50 g of HCl solution. You notice bubbles as a reaction takes place. You then weigh the resulting solution and find that it has a mass of 46.40 g . The relevant equation is CaCO3(s)+2HCl(aq)→H2O(l)+CO2(g)+CaCl2(aq) Assuming no other reactions take place, what mass of CO2 was produced in this reaction? Express your answer to three significant figures and include the appropriate units.

4.10 g so CaCO3 + 2HCl -> H20 + CO2 + CaCl2 input: 10g CaCO3, 40.5 g HCl output: H20 + CaCl2 is 46.4g (the CO2 vaporised) well, if the mass can't dissapear, then the amount of CO2 is (40.5+10)-46.4 = 4.1g

Which element does X represent in the following expression: 41/20X?

41=atomic mass 20= atomic number In this example we only needed the number of protons to identify the symbol of the element. If you were asked to name the isotope, the mass number would be needed as well. In that case the correct answer would be calcium-41.

Calculate the formula mass of ethanol, C2H5OH

46.1 g/mol The formula mass of a molecule, such as ethanol or glucose, is also called the molecular mass. Significant Figures Feedback: Your answer 46.07gmol was either rounded differently or used a different number of significant figures than required for this part.

The ion O2− has _____ protons and _____ electrons.

8,10

Specify the number of protons, neutrons, and electrons in the neutral atom iron-56.

All iron atoms have 26 protons. A neutral Fe atom also has 26 electrons. The sum of the protons and neutrons gives the mass number,26+30=56.

Notice that "SO4" appears in two different places in this chemical equation. SO 2−4 is a polyatomic ion called "sulfate." What number should be placed in front of CaSO4 to give the same total number of sulfate ions on each side of the equation? ?CaSO4+AlCl3→CaCl2+Al2(SO4)3

Answer -> 3 is the number 3CaSO4 + 2AlCl3 --> 3CaCl2 + Al2(S04)3 How to solve: First, write out how many you have of each, like so: reactants: Ca: 1 SO: 4 Al: 1 Cl: 3 Products: Ca: 1 SO: 12 Al: 2 Cl: 2 Then, start with the hardest, which would be getting the same # of Cl on each side. 2&3 go into 6, so put a 3 in front of CaCl2 on the products side and a 2 in front of AlCl3 on the reactants side. What gives you 6 Cl on each side. Then, put a 3 in front of the CaSO4 on the products side, to get 12 SO. Now SO & Cl are balanced. So is Ca, & it became balanced on it's own from what you did with Cl. That leaves Al, just put a 2 in front of it on the products side & bam. Balanced. (: Now that we have put a coefficient of 3 in front of CaSO4, what coefficient should go in front of CaCl2 to balance calcium (Ca)? 3CaSO4+AlCl3→?CaCl2+Al2(SO4)3 By placing a coefficient of 3 in front of calcium chloride, we have indicated three calcium atoms on the right to match the three calcium ions on the left: 3CaSO4+AlCl3→3CaCl2+Al2(SO4)3

What isotope has 18 protons and 22 neutrons?

Argon has 18 protons in its nucleus. It is the only element that has 18 protons. If it had more or fewer protons, it would not be argon. However, the number of neutrons can vary, which is why the mass is written in the name

Part B A certain element X has four isotopes. 94.93% of X has a mass of 31.97207 amu. 0.7640% of X has a mass of 32.97146 amu. 4.290% of X has a mass of 33.96786 amu. 1.600×10−2% of X has a mass of 35.96709 amu. What is the average atomic mass of element X?

Average atomic mass of element X = 31.97207 x 0.9493 + 32.97146 x 0.007640 + 33.96786 x 0.04290 + 35.96709 x 0.00016 = 30.35109 + 0.25190 + 1.45722 + 0.00575 = 32.06596 amu

Mass-to-Mass Conversions in Stoichiometry ? a) What mass of carbon dioxide is produced from the complete combustion of 8.50×10^−3 g of methane? b) What mass of carbon dioxide is produced from the complete combustion of 8.50×10^−3 g of methane? c) What mass of water is produced from the complete combustion of 8.50×10^−3 g of methane? d)What mass of oxygen is needed for the complete combustion of 8.50×10^−3 g of methane?

CH4 + 2O2 >> CO2 + 2 H2O moles CH4 = 8.5 x 10^-3 / 16.043 g/mol = 0.000530 = moles CO2 mass CO2 = 0.000530 mol x 44 g/mol = 0.0233 g moles H2O = 2 x 0.000530 = 0.00106 mass H2O = 0.00106 mol x 18 g/mol = 0.0191 g moles O2 = 2 x 0.000530 = 0.00106 mass O2 = 0.00106 mol x 32 g/mol = 0.0339 g

A certain element forms an ion with 18 electrons and a charge of +2. Identify the element.

Ca *A certain element forms an ion with 18 electrons and a charge of +2. ... Recall that atoms have the same number of electrons as protons, and the atomic number of an atom is the number of protons it has. So, the atom in question is the atom whose atomic number is 20.....that's calcium (Ca)

What is the name of the acid whose formula is H2CO3?

Carbonic Acid

Classify each reaction as a condensation reaction, a redox reaction, or both a condensation and redox reaction.

Condensation only: CaO+CO2--> CaCO3 Redox only: 2H2o--> 2H2+O2, Ca+2HCl--> CaCl2+H2 Both: 2Fe+3Cl2--> 2FeCl3

A certain metal hydroxide, M(OH)2, contains 32.8% oxygen by mass. What is the identity of the metal M?

Copper Mass of oxygen32.8g moles of oxygen 2.05(/16) moles of hydrogen2.05(= in formula) mass of hydrogen 2.05g (*1) Mass of metal 65.15g (by difference from 100) moles of metal 1.03(O /2) so we have 1.03 moles of metal in 65.15 g mass of 1 mole = 63.56 g copper !!

Classify the following compounds as having covalent or ionic bonds

Covalent bonds: Sulfur Trioxide, Phosphorus Trichloride Ionic Bonds: Strontium iodide, aluminum sulfide, barium chloride, potassium iodide **The use of the prefixes mono, di, and tri is also a sign that those compounds contain covalent bonds. Those prefixes are not used in ionic compounds to specify the number of anions in the formula. However, there are a few polyatomic anions that have prefixes in their name, such as dichromate.

When heated, solid copper(II) carbonate decomposes to solid copper(II) oxide and carbon dioxide gas. Give the balanced chemical equation (including phases) that describes this reaction. Indicate the phases using abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively.

CuCO3(s)→CuO(s)+CO2(g)

Blue vitriol is commonly used in industrial dyeing processes. What is the chemical formula for blue vitriol, whose systematic name is copper(II) sulfate?

CuSO4 (4 to the lower power)

Classify each of the following reactions: A. C2H4(g)+3O2(g)→2CO2(g)+2H2O(g) B. MgCO3(s)→MgO(s)+CO2(g) C. 2K(s)+S(s)→K2S(s) D. NH3(g)+HCl(g)→NH4Cl(s) E. 2N2O5(g)→4NO2(g)+O2(g)

Decomposition ( A+B--> C) B, E Combination (D-->E+F) D, C Combustion (Fuel+O2-->CO2+H2O) A

What is the formula for sulfurous acid?

H2SO3 (2 and 3 lower power spot)

What is the name of the acid whose formula is HI?

Hydroiodic acid

Classify the following as intensive or extensive properties of silver.

Intensive: Begins to melt at 961.78 degrees Celsius - matte gray in color - has a density of 10.49 g/mL Extensive: - Has a volume of 7.42 mL - has a mass of 77.83 g

Which of the following properties of a piece of wood are physical properties?

It is hard - it has a mass of 2.3 g. - it is rough to touch

Which of the following properties of zinc are chemical properties?

It reacts with chlorine to form zinc chloride. - it burns under a flame giving off zinc oxide fumes

An air sample consists of oxygen and nitrogen gas as major components. It also contains carbon dioxide and traces of some rare gases. All these gases are evenly distributed throughout the sample of air. Which term or terms could be used to describe this sample of air?

Mixture, Homogeneous mixture, solution. (all solutions are homogeneous mixtures, and all homogeneous mixtures are solutions)

A sample of granite contains various oxides of silicon, aluminum, sodium, potassium, calcium, and iron. Each of these oxides gives the granite a coarse-grained texture. Which term or terms could be used to describe this sample of granite?

Mixture, heterogeneous mixture.

Which of the following would you expect to be a molecule and which would you expect to be part of an ionic solid?

Molecular: CO, NO, HBr Ionic: RbCl, SrO, LiCl, BaS, LiBr

Sodium carbonate is used in the manufacture of paper. What is the chemical formula for this compound?

Na2CO3 (2 and 3 to lower power)

What is the name for the compound NO2?

Nitrogen Dioxide

Match the diagram to the atom or ion it represents

P = 15+ protons -15 Electrons (neutral) P^3+= 15+ Protons, 12- Electrons (positive charge) P^3-=15+ Protons, -18 Electrons (negative charge) Mg= 12+ Protons, 12- Electrons Mg^2+= 12+ Protons, 10- electrons (positive charge) Mg^2-= 12+ protons, 14- electrons (Negative charge)

Monel metal is a corrosion-resistant copper-nickel alloy used in the electronics industry. A particular alloy with a density of 8.80 g/cm3 and containing 0.024 % Si by mass is used to make a rectangular plate that is 15.0 cm long, 12.5 cm wide, and 3.50 mm thick and has a 2.50-cm-diameter hole drilled through its center such that the height of the hole is 3.50 mm . The silicon in the plate is a mixture of naturally occurring isotopes. One of the those isotopes is silicon-30, which has an atomic mass of 29.97376 amu. The percent natural abundance, which refers to the atoms of a specific isotope, of silicon-30 is 3.10%. A. What is the volume of this plate B. How many silicon-30 atoms are found in this plate?

Part A 63.9 cm^3 Part B density = mass / volume volume = (15.0 cm) * (12.5 cm) * (0.350 cm) = 65.625 cm^3 8.80 grams/cm^3 = mass / 65.626 cm^3 mass = 577.5 grams alloy mass of Si in alloy = (5.775grams alloy) * (0.00024) = 0.1386 grams Si mass of Si-30 = (0.1386 grams Si in metal) * (0.0310) = 0.0042966 grams Si-30 atoms Si-30 = (0.0042966 grams Si-30) * (1 mol Si-30 / 29.97376 grams Si-30) * (6.02*10^23 atoms Si-30 / 1 mol Si-30) = 8.629*10^19

An unknown compound contains only carbon, hydrogen, and oxygen (CxHyOz). Combustion of 5.00 g of this compound produced 7.33 g of carbon dioxide and 3.00 g of water. Part A: How many moles of carbon, C, were in the original sample? Part B: How many moles of hydrogen were in the original sample? Part C: If 5.00 g of the unknown compound contained 0.167 mol of C and 0.333 mol of H, how many moles of oxygen, O, were in the sample? Part D: Part complete What is the empirical formula of a substance that contains 0.167 mol of carbon, 0.333 mol of hydrogen, and 0.166 mol of oxygen? Part E: Determine the molecular formula for the unknown if the molecular mass is 60.0 amu and the empirical formula is CH2O.

Part A: 0.167 mol Part B: 0.333 mol Part C: 0.166 mol Part D: CH2O Part E: (Multiply by 2) C2H4O2)

The Haber-Bosch process is a very important industrial process. In the Haber-Bosch process, hydrogen gas reacts with nitrogen gas to produce ammonia according to the equation 3H2(g)+N2(g)→2NH3(g) The ammonia produced in the Haber-Bosch process has a wide range of uses, from fertilizer to pharmaceuticals. However, the production of ammonia is difficult, resulting in lower yields than those predicted from the chemical equation. 1.89 g H2 is allowed to react with 9.82 g N2, producing 1.77 g NH3. Part A: What is the theoretical yield in grams for this reaction under the given conditions?

Part A: 10.7 g Part B: 16.6% (B) Percentage yield = 1.77/10.7*100% = 16.6%

An organic liquid is a mixture of methyl alcohol (CH3OH) and ethyl alcohol (C2H5OH). A 0.220-g sample of the liquid is burned in an excess of O2(g) and yields 0.369 g CO2(g) (carbon dioxide). Part A: Set up two algebraic equations, one expressing the mass of carbon dioxide produced in terms of each reagent and the other expressing the mass of sample burned in terms of each reagent. What is the mass of methyl alcohol (CH3OH) in the sample? Part B: What is the mass percentage of ethyl alcohol, C2H5OH, in the solution?

Part A: Mass of CH3OH: 9.64*10^-2 Part B: 56.2%

Part A: What is the empirical formula for the compound P4O6? Part B: How many grams of each element are in this sample? Part C: How many moles of each element are in this sample? Part D: Based on the mole ratio you determined in part C, what is the empirical formula of this compound?

Part A: P2O3 Part B: C=80.0, H 20.0 g Part C: C=6.66, H=19.8 mol Part D: CH3

A glass jar contains pure sodium chloride. Which term or terms could be used to describe the contents of this glass jar?

Pure chemical substance, compound. (All compounds are pure. If this sample of sodium chloride (NaCl) had been impure, we would call it a mixture, not a compound.)

A sliver necklace is made from a pure sample of silver that is free of impurities. Which term or terms could be used to describe this sample of silver?

Pure chemical substance, element. (all elements are pure. If this sample of silver had been impure, we would call it a mixture, not an element.)

What is the systematic name of NH4ClO3?

ammonium chlorate

What is the name of the covalent compound CCl4?

carbon tetrachloride

A hydrocarbon is a compound that contains mostly carbon and hydrogen. Calculate the percent composition (by mass) of the following hydrocarbon: C 5 H 12 .

carbon, hydrogen = 83.23,16.77 % Notice that the sum of the percentages is 100%. Term 1: Significant Figures Feedback: Your answer 83.2 % was either rounded differently or used a different number of significant figures than required for this part. Term 2: Significant Figures Feedback: Your answer 16.8 % was either rounded differently or used a different number of significant figures than required for this part.

How much does one sucrose molecule weigh in grams?

mass of one molecule of sucrose = 5.68×10^−22 g

What is the name for the compound P4O10?

tetraphosphorus decoxide