Q: A 2.0 L container of nitrogen had a pressure of 5.4 atm. What volume would be necessary to decrease the pressure to 2.0 atm?

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{5.4 \times 2.0}{2.0} = 5.4\ \text{L}$$

Q: When a 25.00 mL sample of $$H_2SO_4 is $$titrated with 0.2453 M $$NaOH$$, 32.47 mL of $$NaOH$$ solution is required. What is the molarity of the $$H_2SO_4$$?

$$M_{H_2SO_4} = \frac{M_{NaOH} \times V_{NaOH}}{2 \times V_{H_2SO_4}} = \frac{0.2453 \times 32.47}{2 \times 25.00} = 0.159\ \text{M}$$

Question 1

Which of the following is NOT a property of gases?

Accepted Answer

Gases have definite shape and volume.

Question 2

A 2.0 L container of nitrogen had a pressure of 5.4 atm. What volume would be necessary to decrease the pressure to 2.0 atm?

Accepted Answer

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{5.4 	imes 2.0}{2.0} = 5.4\ 	ext{L}$$

Question 3

Calculate the number of moles and the mass of gas in 10.2 L of $$O_2 at $$STP.

Accepted Answer

0.455 mol, 14.6 g

Question 4

A balloon is filled with helium at sea level, and then taken into the mountains to an elevation of 7500 feet. Assuming the temperatures are the same, what will happen to the balloon?

Accepted Answer

The balloon expands because the pressure is lower at higher elevation.

Question 5

A molecule contains a central atom with three identical bonds to other atoms and one lone pair. The shape of this molecule is:

Accepted Answer

Trigonal pyramidal

Question 6

The water molecule has a dipole with the negative portion (the head of the arrow) ________.

Accepted Answer

Surrounding the oxygen atom

Question 7

Which of the following intermolecular forces is strongest in $$CH_2O$$?

Accepted Answer

Dipole-dipole

Question 8

What is the pH of a solution with a hydroxide concentration of $$[OH^-] = 1 	imes 10$$^{-3}$$\ 	ext{M}$$?

Accepted Answer

$$pH = 11$$

Question 9

Which of the following substances is a strong electrolyte?

Accepted Answer

$$NaCl$$

Question 10

Which of the following equations describes what happens when $$HCl(g)$$ dissolves in water?

Accepted Answer

$$HCl(g) \rightarrow H^+(aq) + Cl^-(aq)$$

Question 11

Which of the following increases the solubility of a gas in solution?

Accepted Answer

Increasing pressure and decreasing temperature

Question 12

How many moles of $$NaCl$$ are contained in 50.0 mL of 2.50 M $$NaCl$$?

Accepted Answer

0.125 moles

Question 13

When a 25.00 mL sample of $$H_2SO_4 is $$titrated with 0.2453 M $$NaOH$$, 32.47 mL of $$NaOH$$ solution is required. What is the molarity of the $$H_2SO_4$$?

Accepted Answer

$$M_{H_2SO_4} = \frac{M_{NaOH} 	imes V_{NaOH}}{2 	imes V_{H_2SO_4}} = \frac{0.2453 	imes 32.47}{2 	imes 25.00} = 0.159\ 	ext{M}$$

Question 14

Which law describes the relationship between pressure and volume for a fixed amount of gas at constant temperature?

Accepted Answer

Boyle's Law: $$P_1$$ $$V_1$$ = $$P_2$$ $$V_2$$

Question 15

Which of the following best explains why ice floats on water?

Accepted Answer

Ice is less dense than liquid water due to hydrogen bonding.

Question 16

Which of the following acids is correctly named?

Accepted Answer

$$HBr is $$Hydrobromic Acid

Question 17

What is the strongest intermolecular force present in $$H_2S$$?

Accepted Answer

Dipole-dipole

Question 18

Which of the following best describes the effect of temperature on gas solubility in water?

Accepted Answer

Gas solubility decreases as temperature increases.

Question 19

Which equation is used to calculate the number of moles of a gas at STP?

Accepted Answer

$$n = \frac{V}{22.4}$$

Introductory Chemistry Test 4 Study Guidance

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