AP Chemistry First Semester Final

The net ionic equation for the reaction of calcium bromide and sodium phosphate contains what species?

3Ca2+ (aq)

How many grams of potassium are in 12.5 g of K2CrO7?

4.04 g

Calculate the root mean square velocity for the O2 molecules in a sample of O2 gas at 25°C (R=8.3145 J/K mol)

482 m/s

What mass of calcium chloride, CaCl2, is needed to prepare 2.850 L of a 1.56 M solution?

493 g

How many grams of NaCl are contained in 350. mL of a 0.250 M solution of sodium chloride?

5.11 g

Sample of oxygen gas has a volume of 4.50 L at 27°C and 800 torr. How many oxygen molecules does it contain?

1.16×10^23

Calculate the ratio of the effusion rates of N2 and N2O

1.25

A balloon has a volume of 1.20 liters at 24.0°C. The balloon is heated to 48.0°C. Calculate the new volume of the balloon

1.30 L

In 1928, 1.0 g of a new element was isolated from 660 kg of the ore molybdenite. The percent by mass of this element in the ore was

1.5 x 10^4%

A 130 mL sample of gas is collected over water at 22 degrees C and 753 torr. What is the volume of the dry gas gas at STP? (The vapor pressure if water at 22 degrees C is 20 torr)

116 mL

A 25.0 g piece of aluminum (which has a molar heat capacity of 24.03 J/degrees Celsius mol) is heated to 82.4°C and dropped into a calorimeter containing water (specific heat capacity of water is 4.18 g degrees Celsius) initially at 23.3°C the final temperature of the water is 24.9°C. Calculate the mass of water in the calorimeter

118 g

The average mass of a carbon atom is 12.011. Assuming you were able to pick up only one carbon unit, the chances that you would randomly get one with a mass of 12.011 is

0%

A gas sample from -20°C to 57°C and the volume is increased from 2.00 L to 4.50L. If the initial pressure is 0.126 atm, what is the final pressure?

0.0730 atm

A student weighs out 0.568 g of KHP (molar mass= 204 g/mol) and titrates to the equivalence point with 36.78 mL of a stock NaOH solution. What is the concentration of the stock NaOH solution? KHP is an acid with one acidic proton.

0.0757

You measure water in two containers: a 10-mL graduated cylinder with marks at every mL and a 1-mL piper marked at every 0.1 mL. If you have some water in each of the containers, and add them together, to what decimal place could you measure the total?

0.1 mL

You are holding 2 balloons, an orange balloon and a blue balloon. The orange balloon is filled with neon (Ne) gas and the blue balloon is filled with Argon (Ar) has. The orange balloon has twice the volume of the blue balloon. Which of the following best represents the mass ratio of Ne:Ar in the balloons?

1:1

For a gas which two variables are directly proportional to each other (if all other conditions remain constant?) 1. T and N 2. V and N 3. V and T

2 and 3 only

What mass of NaOH is required to react exactly with 25.0 mL of 1.2 M H2SO4

2.4 g

A 5.95-g sample of AgNO3 is reacted with excess BaCl2 according to the equation 2AgNO3 (aq) + BaCl2 (aq) --> Ba(NO3)2 (aq) to give 4.00 g of AgCl. What is the percent yield of AgCl?

79.7%

Vitamin C contains the elements C, H, and O. It is known to contain 40.9% C and 4.58% H by mass. The molar mass of vitamin C has been found to be about 180. The molecular formula for vitamin C is:

C6H8O6

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 conditions of P, T, and n, respectively, are most ideal?

Low P, high T, low n

Which of the following is the least probable concerning five measurements taken in the lab?

The measurements are accurate but not precise

For the reaction of sodium bromide with chlorine gas to form sodium chloride and bromine, the appropriate half-reaction are

ox: 2Br- -> Br2 + 2e- re: Cl2 + 2e- -> 2Cl-

An unknown substance dissolves readily in water but not in benzene (a nonpolar solvent). Molecules of what type are present in the substance?

polar

Calculate the work for the expansion of CO2 form 1.0 L to 2.5L against a pressure of 1.0 atm at constant temperature

-1.5 L atm

A gas absorbs 0.0 J of heat and then performs 15.2 J of work. The change in internal energy of the gas is

-15.2 J

If a 2.15g sample of a gas occupies 750 mL at STP, what is the molar mass of the gas at 125 degrees C

64.2

Gallium consists of two isotopes of masses 68.95 amu and 70.95 amu with abundances of 60.16% and 39.84%, respectively. What is the average atomic mass of gallium?

69.75 amu

BaCl (aq) + AgNO2 (aq) -> AgCl (s) + BaNO2 (aq) The net ionic equation contains which of the following terms: Ag+ (aq), Ba2+ (aq), NO3- (aq), 2NO3- (aq)

Ag+ (aq)

Which of the following statements from Dalton's atomic theory is no longer true, according to modern atomic theory?

All atoms of a given element are identical

bruhs, is chemistry important in our everyday lives?

BRUH YESSSS... hips ‍ hips dont lie

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

NO and NO2

In which of following does nitrogen have an oxidation state of +4: HNO3, NO2, N2O, NH4Cl, NaNO2

NO2

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

ReCl3

T or F The concentration of a salt water solution which sits in an open beaker decreases over time.

false