Q: A sample contains 0.50 mol of $$Na_2SO_4. $$How many sodium ions are present in the sample?

$$1.0 \times 6.022 \times 10$$^{23}$$

Q: A student is asked to prepare 250 mL of 0.10 M NaCl solution. What mass of NaCl (molar mass = 58.44 g/mol) is required?

$$0.10 \times 0.250 \times 58.44 = 1.46 g$$

Q: A student titrates 25.0 mL of HCl with 0.100 M NaOH. If the endpoint is reached after adding 30.0 mL of NaOH, what is the concentration of the HCl solution?

$$C_{HCl} = \frac{0.100 \times 30.0}{25.0} = 0.120 M$$

Question 1

Which of the following best describes the difference between a physical change and a chemical change?

Accepted Answer

A chemical change results in the formation of new substances with different properties, while a physical change does not alter the chemical identity.

Question 2

A student mixes aqueous solutions of NaCl and AgNO$$_3 in a $$test tube. Which type of reaction occurs, and what is the precipitate formed?

Accepted Answer

Double displacement; AgCl

Question 3

Which of the following is the correct balanced equation for the combustion of methane ($$CH_4) in $$oxygen?

Accepted Answer

$$CH_4 + 2O_2$$ \rightarrow $$CO_2 + 2H_2O$

Question 4

A sample contains 0.50 mol of $$Na_2SO_4. $$How many sodium ions are present in the sample?

Accepted Answer

$$1.0 	imes 6.022 	imes 10$$^{23}$$

Question 5

Which statement about the periodic table is correct?

Accepted Answer

Elements in the same group have the same number of valence electrons.

Question 6

A student is asked to prepare 250 mL of 0.10 M NaCl solution. What mass of NaCl (molar mass = 58.44 g/mol) is required?

Accepted Answer

$$0.10 	imes 0.250 	imes 58.44 = 1.46 g$$

Question 7

Which of the following is an example of a heterogeneous mixture?

Accepted Answer

Oil and water

Question 8

If 2.00 g of $$H_2$$ reacts completely with $$O_2 to $$form water, how many grams of water are produced? ($$M_{H_2$} = 2.02 g/$$mol, $$M_{H_2O} = 18.02 g/$$mol)

Accepted Answer

Question 9

Which of the following laboratory safety practices is most important when working with concentrated acids?

Accepted Answer

Always add acid to water, not water to acid.

Question 10

A student titrates 25.0 mL of HCl with 0.100 M NaOH. If the endpoint is reached after adding 30.0 mL of NaOH, what is the concentration of the HCl solution?

Accepted Answer

$$C_{HCl} = \frac{0.100 	imes 30.0}{25.0} = 0.120 M$$

Question 11

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of $$BaCl_2$$ and $$Na_2SO_4$$?

Accepted Answer

$$Ba^{2+} (aq$$) + $$SO_4$$^{2-} (aq) \rightarrow $$BaSO_4 (s$$)$$

Question 12

Which of the following statements about atomic structure is correct?

Accepted Answer

Protons and neutrons have approximately the same mass.

Question 13

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$$CH_2O$$

Question 14

Which of the following is a strong electrolyte in aqueous solution?

Accepted Answer

Sodium chloride ($$NaCl)$$

Question 15

Which of the following best explains why water is a polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, and the molecule has a bent shape.

Question 16

A student needs to determine the molar mass of an unknown gas. Which laboratory technique would be most appropriate?

Accepted Answer

Measuring the density of the gas at known temperature and pressure

Question 17

Which of the following is the correct formula for calculating the percent yield of a chemical reaction?

Accepted Answer

$$\frac{	ext{Actual yield}}{	ext{Theoretical yield}} 	imes 100$$

Question 18

Which of the following is a correct statement about limiting reactants in a chemical reaction?

Accepted Answer

The limiting reactant is the reactant that is completely consumed first, thus determining the amount of product formed.

Question 19

Which of the following is the correct expression for molarity ($$M$$)?

Accepted Answer

$$M = \frac{	ext{moles of solute}}{	ext{volume of solution in liters}}$$

General Chemistry 1A Syllabus and Course Structure

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