Q: Which of the following best describes the concept of density?

The mass of a substance divided by its volume, $$\frac{\text{mass}}{\text{volume}}.$$

Q: If 100 g of water absorbs 4180 J of heat and its temperature increases by 10°C, what is the specific heat capacity of water?

$$4.18\ \text{J/g}^\circ\text{C}$$

Q: Predict the products and phases for the reaction: $$\text{Na}_2\text{SO}_4 (aq) + \text{BaCl}_2 (aq) \rightarrow$$ ?

$$\text{BaSO}_4 (s) + 2\text{NaCl} (aq)$$

Q: Which of the following is the correct net ionic equation for the reaction between $$\text{Na}_2\text{SO}_4 (aq)$$ and $$\text{BaCl}_2 (aq)$$?

$$\text{Ba}^{2+} (aq) + \text{SO}_4$$^{2-}$$ (aq) \rightarrow \text{BaSO}_4 (s)$$

Q: A sample contains 0.5 mol of $$\text{H}_2\text{O}. $$How many molecules of water are present in the sample? ($$N_A = 6.022 \times 10$$^{23}$$ mol$$^{-1}$$)

$$3.011 \times 10$$^{23}$$ molecules

Question 1

Which of the following best describes the concept of density?

Accepted Answer

The mass of a substance divided by its volume, $$\frac{	ext{mass}}{	ext{volume}}.$$

Question 2

A student measures the mass of a metal block to be 250 g and its volume to be 50 cm³. What is the density of the block?

Accepted Answer

$$5\ 	ext{g/cm}^3$$

Question 3

Which formula is used to calculate the specific heat ($$c) of a $$substance?

Accepted Answer

$$q = mc\Delta T$$

Question 4

If 100 g of water absorbs 4180 J of heat and its temperature increases by 10°C, what is the specific heat capacity of water?

Accepted Answer

$$4.18\ 	ext{J/g}^\circ	ext{C}$$

Question 5

Which of the following is the correct definition of average atomic mass?

Accepted Answer

The weighted average of the masses of all naturally occurring isotopes of an element.

Question 6

Given the isotopes of chlorine: $$^{35}	ext{Cl} (75.8$$%, mass = 34.97 u) and $$^{37}	ext{Cl} (24.2$$%, mass = 36.97 u), calculate the average atomic mass of chlorine.

Accepted Answer

$$35.45\ 	ext{u}$$

Question 7

Which of the following is the correct empirical formula for glucose ($$	ext{C}_6	ext{H}_{12}	ext{O}_6$$)?

Accepted Answer

$$	ext{CH}_2	ext{O}$$

Question 8

A compound contains 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula?

Accepted Answer

$$	ext{CH}_2	ext{O}$$

Question 9

Which of the following is the correct formula to calculate the molar mass of a compound?

Accepted Answer

Sum of the atomic masses of all atoms in the chemical formula.

Question 10

Calculate the molar mass of $$	ext{Na}_2	ext{SO}_4 ($$sodium sulfate). (Na = 22.99 g/mol, S = 32.07 g/mol, O = 16.00 g/mol)

Accepted Answer

$$142.05\ 	ext{g/mol}$$

Question 11

Which of the following best describes a chemical reaction?

Accepted Answer

A process in which one or more substances are converted into new substances with different properties.

Question 12

Predict the products and phases for the reaction: $$	ext{Na}_2	ext{SO}_4 (aq) + 	ext{BaCl}_2 (aq) ightarrow$$ ?

Accepted Answer

$$	ext{BaSO}_4 (s) + 2	ext{NaCl} (aq)$$

Question 13

Which of the following is the correct net ionic equation for the reaction between $$	ext{Na}_2	ext{SO}_4 (aq)$$ and $$	ext{BaCl}_2 (aq)$$?

Accepted Answer

$$	ext{Ba}^{2+} (aq) + 	ext{SO}_4$$^{2-}$$ (aq) ightarrow 	ext{BaSO}_4 (s)$$

Question 14

Which statement best distinguishes between empirical and molecular formulas?

Accepted Answer

Empirical formulas show the simplest whole-number ratio of atoms, while molecular formulas show the actual number of atoms in a molecule.

Question 15

A sample contains 0.5 mol of $$	ext{H}_2	ext{O}. $$How many molecules of water are present in the sample? ($$N_A = 6.022 	imes 10$$^{23}$$ mol$$^{-1}$$)

Accepted Answer

$$3.011 	imes 10$$^{23}$$ molecules

Question 16

Which of the following is NOT a type of chemical equation?

Accepted Answer

Empirical equation

Question 17

Which of the following statements about physical and chemical changes is correct?

Accepted Answer

Chemical changes involve the rearrangement of atoms to form new substances.

Question 18

A student is given a mixture of sand and salt. Which method would best separate the two substances?

Accepted Answer

Dissolve the mixture in water, filter to remove sand, then evaporate the water to recover salt.

Question 19

Which of the following is a correct statement about the law of conservation of mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Core Concepts in Introduction to Chemistry: Measurement, Chemical Composition, and Reactions

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