Exam 1
scientific method
- A series of steps followed to solve problems including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions. - observation ("what" / data / law), hypothesis ("why") experiment, theory (model / "why") prediction, and experiment
theory
- a model - a set of tested hypothesis that gives an overall explanation of a natural phenomenon - explains why nature behaves a certain way - constantly refined or replaced as more information becomes available - explains observed natural behavior in terms of human experiences
Humans have believed matter is composed of _______ Recent development:
- atoms - recent development is that individual atoms can be viewed by using a scanning tunneling microscope (STM) which uses an electron current from a tiny needle to probe the surface of a substance
pure substances are either
- compound: substance with a constant composition that can be broken down into its elements via chemical processes - element: substance that cannot be broken down into simpler substances by physical or chemical means
distillation
- depends on the differences in the volatility of the components
observations
- events witnessed and can be recorded - natural law: a summary of observed (measurable) behavior - Ex: law of conservation of mass, which states that the total mass of materials is unaffected by a chemical change in those materials
Antoine Lavoisier
- explained the true nature of combustion - regarded measurement as the essential operation of chemistry - verified the law of conservation of mass: mass is neither created nor destroyed in a chemical reaction - conducted quantitative experiments that showed that combustion involved oxygen not phlogiston
chromatography
- general name applied to a series of methods that use a system of two states (phases) of matter
You want to order a bike with a 25.5 in grams, but he sizes in the catalog are given only in centimeters. What size should you order?
- have to convert from inches to centimeters - 2.54 cm = 1 in - ans: 64.8 cm
law versus theory
- law is a statement on generally observed behavior; summarizes what happened - theory: human inventions; attempts to explain why something happens
random error
- measurement has an equal probability of being low or high - occurs in estimating the value of the last digit of a measurement (AKA intermediate error)
significant figures
- numbers in which certain digits and the first uncertain digit are recorded
systematic error
- occurs in the same direction each time - either always high or always low (AKA determinant error)
alpha particles beamed at thin metal foil may
- pass directly through without changing direction - be slightly diverted by attraction to electrons - be reflected by direct contact with nuclei
Robert Boyle
- performed quantitative experiments to measure the relationship between the pressure and volume of air - developed the first experimental definition of an element
Joseph Proust
- proposed the principle of the constant composition of compounds or Proust's law of the law of definite proportions - law says a given compound always contains exactly the same proportion of elements by mass
Georg Stahl
- suggested that a substance called a phlogiston flowed out of burning material - postulated that substances that burn in close containers eventually stop burning since the air in the container is saturated with phlogiston
filtration
- used when a mixture consists of a solid and a liquid - mixture is pouring onto a mesh
John Daltons Law of Multiple Proportions
- when two elements form a series of compounds, the ratios of the masses of the second element that combine with 1 g of the first element can always be reduced to small whole numbers
deci centi milli micro nano
0.1 (10^-1) 0.01 (10^-2) 0.001 (10^-3) 0.000001 (10^-6) 0.000000001 (10^-9)
manganese makes up 1.3 × 10⁻⁴ percent by mass of the elements found in a normal healthy body. How many grams of manganese would be found in the body of a person weighing 274 lb? (2.205 lb = 1 kg)
0.16
NaHCO₃ is the active ingredient in baking soda. How many grams of oxygen are in 0.30 g of NaHCO₃
0.17
express the volume 329.0 cm³ in liters
0.3290 L
tera giga mega kilo
1,000,000,000,000 (10^12) 1,000,000,000 (10^9) 1,000,000 (10^6) 1,000 (10^3)
volume: 1 L = 1 ft³ =
1.06 qt 28.32 L
Length: 1 m = 2.54 cm =
1.094 yd 1 in
Express 165,000 in exponential notation.
1.65 × 10⁵
a monolayer containing 3.21 × 10⁻⁶ g of oleic acid has an area of 20.0 cm². The density of oleic acid is 0.895 g / mL. What is the thickness of the monolayer (the length of an oleic acid molecule)
1.79 × 10⁻⁷
how many protons and electrons does the most stable ion for magnesium have
12 protons and 10 electrons
how should the number 1.230 × 10³ be properly expressed as a decimal
1230
what is the mass of a 4.110-mol sample of sodium hydroxide?
164.4
consider the following reaction: CH₄ + 4Cl₂ −> CCl₄ + 4HCl What mass of CCl₄ is formed by the reaction of 1.93 g of methane with an excess of chlorine
18.5 g
the number of protons, neutrons, and electrons in ³⁹₁₉K⁺ are
19 protons, 20 neutrons, and 18 electrons
balance this equation using the smallest possible integers, S + HNO₃ −> H₂SO₄ + NO₂ + H₂O. What is the coefficient of water?
2
indium reacts with chlorine to form InCl₃. In the balanced equation for this reaction, the coefficient of the indium trichlorate is
2
mass: 1 kg = 452.6 =
2.205 lb 1 lb
the mineral pyromorphite has the formula Pb₅(PO₄)₃Cl. What is the mass percent of chlorine does it contain?
2.61%
⁴⁰₂₀C²⁺ has
20 protons, 20 neutrons, and 18 electrons
express the number 2.07 × 10⁴ in common decimal form
20700
what is the best answer report for (749 × 0.0043) + 22.97?
26.2
when 87.7 is added to 73.841, the result should be reported with _____ significant figures. And when 87.7 is divided by 73.841 the result should be reported with ____ significant figures
3 and 3
How many sigfigs are in 1.05 × 10⁻³ ÷ 6.135
3 sig figs
Consider the following reaction: CH₄ + 4Cl₂ −> CCl₄ + 4HCl What mass of CCl₄ will be formed if 1.20 moles of methane react with 1.07 moles of chlorine
41.1 g
Consider the fermentation reaction of glucose: C₆H₁₂O₆ −> 2C₂H₅OH + 2CO₂ A 1.00 mole sample of C₆H₁₂O₆ was placed in a vat with 100 g of yeast. If 39.6 grams of C₂H₅OH was obtained, what was the percent yield of C₂H₅OH?
43.0%
a 20.0 mL sample of glycerol has a mass of 25.8 grams. What is the density of glycerol in ounces / quart? (1.00 ounce = 28.4 grams, and 1.00 liter = 1.06 quarts)
49.2 oz/qt
calculate 5.1234 + 0.033 ÷ 1.650 and report to the correct number of significant figures
5.1
5.3 seconds contains how many picoseconds
5.3 × 10¹²
each molecule of lycopene contains 40 atoms of carbon (plus other atoms). The mass percent of carbon in lycopene is 84.49%. What is the molar mass of lycopene
568.6 g/mol
the empirical formula of a group of compounds is CHCl. Lindane, a powerful insecticides is a member of this group. The molar mass of lindane is 290.8% g/mol. How many atoms of carbon does a molecule of lindane contain?
6
a wavelength of red light is measured at 655 nm. What Is this measurement in cm?
6.55 × 10⁻⁵
convert 40.8 mi to km (1 m = 1.094 yd, 1 mi = 1760 yd)
6.56 × 10¹
the reaction of 11.9 g of CHCl₃ with excess chlorine produced 10.1 grams of CCl₄, carbon tetrachloride: 2CHCl₃ + 2Cl₂ −> 2CCl₄ + 2HCl what is the percent yield?
65.7%
nitric oxide, NO, is made from the oxidation of NH₃, and the reaction is represented by the equation: 4Nh₃ + 5O₂ −> 4NO + 6H₂O A 9.8 g sample of NH₃ gives 12.0 grams of NO. The percent yield of NO is
69%
a piece of idiom with a mass of 21.93 g is submerged in 46.3 cm³ of water in a graduated cylinder. The water level increases to 49.3 cm³. The correct value for the density of idiom from this data is:
7.3 g / cm³
7.6 kilograms contains how many grams
7.6 × 10³
what is the sum of the coefficients of the following equation when it is balanced using the smallest whole numbers? NaNH₂ + NaNO₃ −> NaN₃ + NaOH + NH₃
9
how many grams of H₂O will be formed when 32.0 g H₂ is mixed with 84.0 g of O₂ and allowed to react to form water
94.6 g
which of the following names is incorrect? A. Cobalt (II) chloride B. Magnesium oxide C. aluminum (III) oxide D diphosphorus pentoxide E. all are correct
C
matter
anything that occupies space and has mass - exists in solid, liquid, and gas
matter is composed of various types of
atoms
which of the following statements from daltons atomic theory is no longer true, according to modern atomic theory
atoms are indivisible in chemical reactins
which of the following pairs is incorrect? a. NH₄Br, ammonium bromide b. K₂CO₃, potassium carbonate c. BaPO₄, barium phosphate d. CuCl, copper (I) chloride e. MnO₂, manganese (IV) oxide
c
in balancing an equation, we change the _______ to make the number of atoms on each side of the equation balance
coefficients of compounds
_________ are the substances with constant composition that can be broken down into elements by chemical processes
compounds
all of the following are in aqueous solution. Which is incorrectly named? a. H₂SO₄, sulfuric acid b. H₂CO₃, carbonic acid c. H₃PO₄, phosphoric acid d. HCN, cyanic acid e. HCl, hydrochloric acid
d
properties of a liquid
definite volume, no specific shape, slightly compressible
percision
degree of agreement among several measurement of the same quantity
Georg Bauer
developed systematic metallurgy
Paracelsus
discovered the medicinal application of minerals
weight
force exerted by gravity on an object - varies with the strength go the gravitational field
heterogeneous mixture
has visibly distinguishable parts
homogeneous mixture
has visibly indistinguishable parts and is often called a solution
a solution is also a:
homogeneous mixture
properties of a substance can be determined by the way
in which atoms are oganixedh in that substance - Ex: Water has two atoms, hydrogen and oxygen
a measurement always has some degree of
uncertainty
Kelvin =
°C + 273.15
Celsius =
°K - 273.15
which has 61 neutrons, 47 protons and 46 electrons
¹⁰⁸₄₇Ag⁺
all of the following are true except: A. ions are formed by adding electrons to a neutral atom B. ions are formed by changing the number of protons in an atoms nucleus C. ions are formed by removing electrons from a neutral atom D. an ion has a positive or negative charge E. metals tend to form positive ions
B
adipic acid contains 19.32% C, 43.84% O, and 6.85% H by mass. What is the empirical formula?
C₃H₅O₂
an unknown molecule is found to consist of 24.2% carbon by mass, of 4.0% hydrogen by mass and the remaining mass is due to chlorine. What is the molecular formula of the molecule given that the molar mass is found to be approximately 150?
C₃H₆Cl₃
the empirical formula of styrene is CH; its molar mass is 104.1 g/mol. What is the molecular formula of styrene
C₈H₈
a species with 12 protons and 10 electrons is
Mg²⁺
which of the following compounds is named incorrectly? a. Mg(OH)₂ is magnesium dihydroxide b. CaO is calcium oxide c. NH₄NO₃ is ammonium nitrate d. K₃PO₄ is potassium phosphate e. MgSO₃ is magnesium sulfite
a
accuracy
agreement of a particular value with the true value
which of the following name(s) is (are) correct? 1. sulfide, S²⁻ 2. ammonium chloride, NH₄Cl 3. acetic acid, HC₂H₃O₂ 4. Barium oxide, BaO A. all B. none C. 1, 2 D. 3, 4 E. 1, 3, 4
all
_____ is the agreement of a particular value with the true value
accuracy
mass
measure of the resistance of an object to a change in its state of motion - measured by the force necessary to give an object a certain acceleration
The statement "the total mass of materials is not affected by a chemical change in those materials" is called
natural law
properties of a gas
no fixed volume, highly compressible
according to the law of multiple proportions: A. if the same two elements from two different compounds, they do so in the same ratio B. it is not possible for the same two elements to form more than one compound C. the ratio of the masses of the elements in a compound is always the same D. the total mass after a chemical change is the same as before the change E. none of these
none of these
the boiling point of water is a
physical change because the gaseous water is chemically the same as the liquid
as part os the calibration of a new laboratory balance, a 1.000-g mass is weighed with the following: 1.201, 2.202, and 1.200. The balance is
precise but inaccurate
_______ reflects the reproducibility of a given type of measurement
precision
observations can be
qualitative (no numbers) or quantitative (measurements)
properties of a solid
rigid, fixed volume and shape, slightly compressible
mixtures can be
separated into pure substances, which has constant compositions, by physical methods
