Question 1

A student is given a mixture of sand, salt, and iron filings. Which sequence of separation techniques would best separate all three components?

Accepted Answer

Use a magnet to remove iron filings, dissolve the remaining mixture in water, then filter to separate sand, and finally evaporate the water to recover salt.

Question 2

Which of the following best describes the difference between accuracy and precision in a set of measurements?

Accepted Answer

Accuracy refers to how close measurements are to the true value, while precision refers to how close measurements are to each other.

Question 3

A sample of ethanol has a mass of 46.0 g and occupies a volume of 58.0 mL. What is its density?

Accepted Answer

$$0.793\ \mathrm{g/mL}$$

Question 4

Which experiment led to the discovery of the electron, and what was the key observation?

Accepted Answer

Thomson's cathode ray tube experiment; observation that cathode rays were deflected by electric and magnetic fields.

Question 5

A naturally occurring element consists of two isotopes: $$^{35}\mathrm{Cl} ($$mass = 34.97 u, abundance = 75.8%) and $$^{37}\mathrm{Cl} ($$mass = 36.97 u, abundance = 24.2%). What is the average atomic mass of chlorine?

Accepted Answer

$$35.45\ \mathrm{u}$$

Question 6

Which of the following compounds is ionic and which is covalent? (I) $$\mathrm{NaCl} (II$$) $$\mathrm{CO_2$} ($$III) $$\mathrm{H_2O} (IV$$) $$\mathrm{MgO}$$

Accepted Answer

Ionic: I, IV; Covalent: II, III

Question 7

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

Accepted Answer

$$\mathrm{CH_2O}$$

Question 8

Balance the following equation and identify the type of reaction: $$\mathrm{C_3H_8} + \mathrm{O_2$} \rightarrow \mathrm{CO_2$} + \mathrm{H_2O}$$

Accepted Answer

Balanced: $$\mathrm{C_3H_8} + 5\mathrm{O_2$} \rightarrow 3\mathrm{CO_2$} + 4\mathrm{H_2O}$$; Combustion reaction

Question 9

A student mixes $$50.0\ \mathrm{mL} of$$ $$0.200\ \mathrm{M}$$ $$\mathrm{NaCl}$$ with $$100.0\ \mathrm{mL} of $$water. What is the final concentration of $$\mathrm{NaCl}$$?

Accepted Answer

$$0.067\ \mathrm{M}$$

Question 10

Which of the following best describes a chemical change?

Accepted Answer

Iron rusting in moist air.

Question 11

A solution is prepared by dissolving $$5.85\ \mathrm{g} of$$ $$\mathrm{NaCl} in $$enough water to make $$500.0\ \mathrm{mL} of $$solution. What is the molarity of the solution? ($$\mathrm{NaCl}$$ molar mass = $$58.5\ \mathrm{g/mol})$$

Accepted Answer

$$0.200\ \mathrm{M}$$

Question 12

Which of the following is a net ionic equation for the reaction between aqueous solutions of $$\mathrm{$$AgNO_3$$}$$ and $$\mathrm{NaCl}$$?

Accepted Answer

$$\mathrm{Ag^+} (aq) + \mathrm{Cl^-} (aq) \rightarrow \mathrm{AgCl} (s)$$

Question 13

A $$25.0\ \mathrm{mL}$$ sample of $$0.100\ \mathrm{M}$$ $$\mathrm{HCl} is $$titrated with $$0.250\ \mathrm{M}$$ $$\mathrm{NaOH}. $$What volume of $$\mathrm{NaOH} is $$required to reach the equivalence point?

Accepted Answer

$$10.0\ \mathrm{mL}$$

Question 14

Which of the following best describes a homogeneous mixture?

Accepted Answer

A glass of salt water.

Question 15

Which of the following is the correct formula for sulfuric acid?

Accepted Answer

$$\mathrm{H_2SO_4}$$

Question 16

A reaction has a theoretical yield of $$10.0\ \mathrm{g}$$ but only $$7.5\ \mathrm{g} of $$product is actually obtained. What is the percent yield?

Accepted Answer

$$75\%$$

Question 17

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 18

A sample of gas is measured at $$27^\circ\mathrm{C}. $$What is the temperature in Kelvin?

Accepted Answer

$$300\ \mathrm{K}$$

Question 19

Which of the following best describes the process of solvation for an ionic solute in water?

Accepted Answer

Water molecules surround and separate the positive and negative ions, stabilizing them in solution.

General Chemistry Study Guide: Matter, Atoms, Stoichiometry, and Reactions in Solution

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