chem 1 exam 1

The oxidation state of iodine in IO3- is:

+5

A scientist obtains the number 0.045006700 on a calculator. If this number actually has four (4) significant figures, how should it be written?

0.04501

A 7.11-g sample of potassium chlorate was decomposed according to the following equation: 2KClO3 → 2KCl + 3O2 How many moles of oxygen are formed?

0.0870 mol

For the reaction N2(g) + 2H2(g) N2H4(l), if the percent yield for this reaction is 82.0%, what is the actual mass of hydrazine (N2H4) produced when 25.57 g of nitrogen reacts with 4.45 g of hydrogen?

24.0 g N2H4

When sodium chloride and lead(II) nitrate react in an aqueous solution, which of the following terms will be present in the balanced molecular equation?

2NaNO3(aq)

You mix 55 mL of 1.00 M silver nitrate with 25 mL of 0.84 M sodium chloride. What mass of silver chloride should you form?

3.0 g

Express the number 0.000333 in scientific notation.

3.33 x 10^-4

Which of the following aqueous solutions contains the greatest number of ions?

300.0 mL of 0.10 M CaCl2

Bromine exists naturally as a mixture of bromine-79 and bromine-81 isotopes. An atom of bromine-79 contains

35 p, 44 n, 35 e

Convert 0.3980 m to mm.

398.0 mm

The net ionic equation for the reaction of aluminum sulfate and sodium hydroxide contains which of the following species?

3OH-(aq)

Consider the numbers 23.68 and 4.12. The sum of these numbers has ____ significant figures, and the product of these numbers has ____ significant figures.

4,3

Nitric oxide, NO, is made from the oxidation of NH3, and the reaction is represented by the equation: 4NH3 + 5O2 → 4NO + 6H2O An 8.7-g sample of NH3 gives 12.0 g of NO. The percent yield of NO is

78%

How many atoms of hydrogen are present in 7.63 g of ammonia?

8.09 x 1023

8.1 kilogram(s) contains this many grams.

8.1 x10^3

Convert 59.4 mi to km. (1 m = 1.094 yd, 1 mi = 1760 yd)

9.56 x 10^1

You are given a compound with the formula MCl2, in which M is a metal. You are told that the metal ion has 26 electrons. What is the identity of the metal?

Ni

As part of the calibration of a new laboratory balance, a 1.000-g mass is weighed with the following results: Trial Mass 1 1.201 + 0.001 2 1.202 + 0.001 3 1.200 + 0.001 The balance is:

Precise but inaccurate.

A chloride of rhenium contains 63.6% rhenium. What is the formula of this compound?

ReCl3

The scientist whose alpha-particle scattering experiment led him to conclude that the nucleus of an atom contains a dense center of positive charge is

Rutherford

Naturally occurring element X exists in three isotopic forms: X-28 (27.977 amu, 92.23% abundance), X-29 (28.976 amu, 4.67% abundance), and X-30 (29.974 amu, 3.10% abundance). What is the identity of element X?

Si

All of the following are in aqueous solution. Which is incorrectly named?

HCN, cyanic acid

Which of the following is a strong acid?

HClO4

The agreement of a particular value with the true value is called

accuracy

An example of a pure substance is

all of these

All of the following are characteristics of nonmetals except:

appear in the upper left-hand corner of the periodic table

The amount of uncertainty in a measured quantity is determined by:

both the skill of the observer and the limitations of the measuring instrument

In balancing an equation, we change the __________ to make the number of atoms on each side of the equation balance.

coefficients of compounds

A quantitative observation

contains a number and a unit

The Greeks proposed that matter consisted of four fundamental substances:

fire, earth, water, air

The limiting reactant in a reaction

has the lowest ratio of moles available/coefficient in the balanced equation

A solution is also called a

homogeneous mixture

The interaction between solute particles and water is called

hydration

The correct name for FeO is

iron (II) oxide

A metric unit for length is

kilometer

The state of matter for an object that has a definite volume but not a definite shape is

liquid state

What is the measure of resistance an object has to a change in its state of motion?

mass

Order the four metric prefixes from smallest to largest.

nano- < milli- < centi- < kilo-

Generally, observed behavior that can be formulated into a statement, sometimes mathematical in nature, is called a(n)

natural law

We generally report a measurement by recording all of the certain digits plus ____ uncertain digit(s).

one

Which best represents a gaseous compound?

option c

Which best represents a homogeneous mixture of an element and a compound?

option e

The correct name for P3- is

phosphide ion

Which of the following pairs is incorrect?

phosphorus pentoxide, P2O5

The boiling of water is a

physical change because the gaseous water is chemically the same as the liquid

The following reactions: Pb2+ + 2I- → PbI2 2Ce4+ + 2I- → I2 + 2Ce3+ HOAc + NH3 →NH4+ + OAc- are examples of

precipitation, redox, and acid-base reactions, respectively

The degree of agreement among several measurements of the same quantity is called __________. It reflects the reproducibility of a given type of measurement.

precision

In the reaction N2(g) + 3H2(g) → 2NH3(g), N2 is

reduced

Which metals form cations with varying positive charges?

transition metals

When solutions of strontium chloride and sodium sulfate react, which of the following is a spectator ion?

two of these

wPCl5 + xH2O → yPOCl3 + zHCl The above equation is properly balanced when:

w = 1, x = 1, y = 1, z = 2

NaHCO3 is the active ingredient in baking soda. How many grams of oxygen are in 0.52 g of NaHCO3?

0.30 g

Which of the following metric relationships is incorrect?

1 gram = 103 kilograms

How many moles of hydrogen sulfide are contained in a 49.7-g sample of this gas?

1.46 mol

A sample of ammonia has a mass of 43.5 g. How many molecules are in this sample?

1.54 x 1024 molecules

Given the reaction: 2MnO4- + 5H2O2 + 6H+ → 2Mn2+ + 8H2O + 5O2 determine the number of electrons involved in this reaction.

10

409 Kelvin equals

136°C

The atomic mass of rhenium is 186.2. Given that 37.1% of natural rhenium is rhenium-185, what is the other stable isotope?

187,75 Re

A sample of chemical X is found to contain 5.0 grams of oxygen, 10.0 grams of carbon, and 20.0 grams of nitrogen. The law of definite proportion would predict that a 70 gram sample of chemical X should contain how many grams of carbon?

20 grams

Which among the following represent a set of isotopes. Atomic nuclei containing

20 protons and 20 neutrons, 20 protons and 22 neutrons and 21 protons and 19 neutrons, 21 protons and 20 neutrons

What is the molar mass of cryolite (Na3AlF6)?

210.0 g/mol

A 16.4-g sample of HF is dissolved in water to give 2.0 × 102 mL of solution. The concentration of the solution is:

4.1 M

What is the mass of 4 atom(s) of copper in grams?

4.22 x 10-22 g

What is the molar mass of ethanol (C2H5OH)?

46.07 g/mol

Consider the following reaction: What mass of CCl4 is formed by the reaction of 5.14 g of methane with an excess of chlorine?

49.3 g

What mass of NaOH is required to react exactly with 25.0 mL of 2.7 M H2SO4?

5.4 g

How many grams of NaCl are contained in 350. mL of a 0.287 M solution of sodium chloride?

5.87 g

If 45.0 g of O2 are mixed with 45.0 g of H2 and the mixture is ignited, what mass of water is produced?

50.7 g

A 74.28-g sample of Ba(OH)2 is dissolved in enough water to make 2.450 liters of solution. How many mL of this solution must be diluted with water in order to make 1.000 L of 0.100 M Ba(OH)2?

565 mL

The empirical formula of a group of compounds is CHCl. Lindane, a powerful insecticide, 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

An analytical procedure requires a solution of chloride ions. How many grams of NaCl must be dissolved to make 1.95 L of 0.0561 M Cl-?

6.39 g

How many significant figures are there in the number 0.04560700?

7

A piece of zinc with a mass of 12.14 g is submerged in 46.3 cm3 of water in a graduated cylinder. The water level increases to 48.0 cm3. The correct value for the density of zinc from these data is:

7.1 g/cm3

A substance contains 35.0 g nitrogen, 5.05 g hydrogen, and 60.0 g of oxygen. How many grams of hydrogen are there in a 153-g sample of this substance?

7.72 g

Naturally occurring copper exists in two isotopic forms: 63Cu and 65Cu. The atomic mass of copper is 63.55 amu. What is the approximate natural abundance of 63Cu?

70%

A hypothetical element consists of two isotopes of masses 69.95 amu and 71.95 amu with abundances of 25.7% and 74.3%, respectively. What is the average atomic mass of this element?

71.4 amu

Which of the following salts is insoluble in water?

AgCl

Which of the following reactions does not involve oxidation-reduction?

All are oxidation-reduction reactions.

If the Thomson model of the atom had been correct, Rutherford would have observed:

Alpha particles going through the foil with little or no deflection.

An ion is formed

By either adding or subtracting electrons from the atom

The empirical formula of styrene is CH; its molar mass is 104.1 g/mol. What is the molecular formula of styrene?

C8H8

A hydrocarbon (a compound consisting solely of carbon and hydrogen) is found to be 85.6% carbon by mass. What is the empirical formula for this compound?

CH2

Consider an aqueous solution of calcium nitrate added to an aqueous solution of sodium phosphate. What is the formula of the solid formed in the reaction?

Ca3(PO4)2

_________ are substances with constant composition that can be broken down into elements by chemical processes.

Compounds

How many of the following postulates of Dalton's atomic theory are still scientifically accepted?

Compounds are combinations of different atoms.

Which of the following statements is false?

Compounds can exist as atoms or molecules.

Aqueous solutions of sodium sulfide and copper(II) chloride are mixed together. Which statement is correct?

CuS will precipitate from solution.

Phosphoric acid can be prepared by reaction of sulfuric acid with "phosphate rock" according to the equation: Ca3(PO4)2 + 3H2SO4 → 3CaSO4 + 2H3PO4 Suppose the reaction is carried out starting with 129 g of Ca3(PO4)2 and 97.4 g of H2SO4. Which substance is the limiting reactant?

H2SO4

Which of the following statements concerning these figures is correct?

Figure I represents random error and Figure II represents systematic error.

Consider the following three archery targets: Which of the following figure(s) represent a result having high precision?

Figure II and Figure III

Which compound contains the highest percent by mass of hydrogen?

H2O

The density of gasoline is 0.7025 g/mL at 20°C. When gasoline is added to water:

It will float on top.

Which of the following compounds is soluble in water?

K3PO4

You have equal masses of different solutes dissolved in equal volumes of solution. Which of the solutes would make the solution having the highest molar concentration?

LiOH

A species with 12 protons and 10 electrons is

Mg2+

Which of the following pairs of compounds can be used to illustrate the law of multiple proportions?

NO and NO2

In which of the following does nitrogen have an oxidation state of +4?

NO2

You have a sample of zinc (Zn) and a sample of aluminum (Al). You have an equal number of atoms in each sample. Which of the following statements concerning the masses of the samples is true?

The mass of the zinc sample is more than twice as great as the mass of the aluminum sample.

Which of the following is an example of a quantitative observation?

The temperature of the liquid is 60°C.

The formula of water, H2O, suggests:

There are two hydrogen atoms and one oxygen atom per water molecule.