chemistry Exam 2 PDF

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Which of the following is a polar molecule? hydrogen bonding and more more of chemistry exam question...

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New York City College of Technology Department of Chemistry

CHEM 1000 Review for Exam 2 Part I. Multiple Choices: Select the best answer. 1.

The chemical equation below is unbalanced. What is the coefficient of water, H 2O(l) when the equation is balanced? Mg(OH)2(s) + 2 HCl (g)  MgCl2(s) + __ H2O(l) A) 1

2.

3.

B) 2

C) 3

D) 4

E) No coefficient

Answer: B

Which of the following is a polar molecule? A. CO2 B. CH4 C. H2O D. CCl4 E. C2H6 Answer: C Which of the following is a correct mole ratio for the reaction: N2 + 3 H2  2 NH3 ? A. 3 moles H2 B. 2 moles NH3 C. 1 mole N2 1 mole N2 3 moles H2 2 moles NH3 D. All of the above ratios are correct Answer: D

E. None is correct

4.

The Law of Conservation of Mass is the basis of balancing chemical equations. Which of the following is a statement of this Law? A) The masses of the reactants in a chemical reaction are always equal. B) The mass of the product formed in a chemical reaction is determined by the limiting reactant. C) The mass of the product formed in a chemical reaction is equal to the mass of the reactant in the smallest amount. D) Matter is neither gained nor lost in a chemical reaction. E) When two or more products are formed in a chemical reaction; their masses will always be equal. Answer: D 5.

Which one of the following substances has hydrogen bonding? A NH3 B. CH4 C. H-Br D. H-I Answer: A

E. H2

6.

Which symbol, often found in chemical equations, indicates that a substance is dissolved in water? A) (w) B) (l) C) (aq) D) (d) E) (g) Answer: C

7.

How many iron atoms are present in 0.552 mol of iron?

A) 2.80 x1024 D )3.32x1023

8.

B) 6.02x 1023 E) 55.85

C) 27.98 Answer: D

Consider the two beakers labeled A and B. Beaker A contains 1 mole of iron atoms, and

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Exam 2

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Beaker B contains 1 mole of lead atoms. Which statement concerning these samples is known with certainty?

A) A and B contain an equal number of atoms. B) Beakers A and B contain equal masses of atoms. C) Beakers A and B contain an equal volume of atoms. D) Beakers A and B contain samples with the same density. E) None of the above is known with certainty. Answer: A 9.

Which reactions below exemplify single replacement reaction? Check all that apply. A) 2Al(s) + 3H2SO4(aq) → Al2(SO4)3(aq) + 3H2(g) B) SO2(g) + H2O(l) → H2SO3(g) C) LiOH(aq) + HNO3(aq) → LiNO3(aq) + H2O(l) D) 2KBr(aq) + Cl2(g) → 2KCl(aq) + Br2(l) E) CaBr2(aq) + H2SO4(aq)  CaSO4(s) + 2HBr(g) ANS: A, D

10.

Which of the following represents a combination reaction? A. 2C2H6(g) + 7O2(g)  4CO2(g) + 6H2O(l) B. 2KBr(aq) + Cl2(g)  2KCl(aq) + Br2(l) C. N2(g) + 3H2(g)  2NH3(g) D. CaBr2(aq) + H2SO4(aq)  CaSO4(s) + 2HBr(g) E. 2Al(s) + 3H2SO4(aq)  Al2(SO4)3(aq) + 3H2(g) ANS: C

11.

What type of reaction is the following? C2H4 (g) + 3 O2(g) → 2 CO2(g) + 2 H2O(g) A. Combination reaction B. Disproportionation reaction C. Acid-base neutralization reaction D) Combustion reaction E. Hydrogen displacement reaction ANS. D

12.

Dinitrogen monoxide, or laughing gas (N2O), is used as a dental anesthetic and as an aerosol propellant. How many molecules of N2O are present in a 12.6 g sample of the compound? Hint: First, change grams to moles. A. 1.72  1023 molecules D. 7.59  1024 molecules B. 1.289 molecules E. 5.14  1023 molecules

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Exam 2

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C. 3.34  1026 molecules ANS: A 13.

A sample of helium gas occupies 0. 355L at 23°C. If the container of He is expanded to 1.50 L at constant pressure, what is the final temperature for the He at this new volume? A. 1,250 °C B. 978 °C C. 70.1 °C D. 80.0 °C E.1,520 °C ANS: B

14.

The gas pressure in an aerosol can is 1.8 atm at 25°C. If the gas is an ideal gas, what pressure would develop in the can if it were heated to 475°C? A) 0.095 atm B) 0.72 atm C) 3.3 atm D) 4.5 atm E) 34 atm ANS: D

15.

If the pressure of a gas sample is quadrupled and the absolute temperature is doubled, by what factor does the volume of the sample change? A) 8 B) 2 C) 1/2 D) 1/4 E) 1/8 ANS: C

16.

17.

What is the effect of adding distilled water on salt solution? A. mass of solute increases. B. mass of solute remains the same. C. mass of solvent remains the same. D. mass of solution remains the same. E. None of the above ANS: B 250 mL of 6.0 M glucose solution is diluted to 1000 mL with water. What is the new molarity of the glucose solution? A. 1.5 M B. 2.0 M C. 3.0 M D. 6.0 M E. 24 M ANS: A

18.

19.

20.

What is the formula mass of carbon dioxide? A) 28.01 amu B) 28.01 g D) 44.01 g E) 44.01 mol ANS: C What is the molar mass of Ca(OH)2? A. 40.1 g B. 57.1 g ANS: C

C. 74.1 g

C) 44.01 amu

D. 148.2 g

What is the mass of a 0.0200 mol sample of nicotine? [molar mass: nicotine, 162.2 g/mole] A) 1.23 x 10-4 g B) 0.308 g C) 3.24 g D) 32.4 g E) 8.11 x 103 g

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Exam 2

E. none of these

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21.

22.

ANS: C An saturated solution of NaCl at room temperature can dissolve additional mass of NaCl. A. True B. False ANS: B A gas mixture containing oxygen, nitrogen and neon exerts a total pressure of 1.20 atm. If helium is added to the mixture it increases the pressure to 1.50 atm. What is the partial pressure of helium? A. 0.30 atm B. 0.80 atm C. 1.20 atm D. 2.00 atm E. 3.20 atm

ANS: A 23.

24.

25.

26.

27.

28.

29.

The gas law which gives the relationship between volume and temperature at constant pressure and amount of gas is A. Avogadro’s Law B. Charles’ Law C. Boyle’s Law D. Dalton’s Law ANS: B Which of the following pressure measurements is not equal to the others? A. 760 torr B. 760 mm Hg D. 76.0 cmHg E. 100 Pascals ANS: E

C. 1 atm

An anesthetic consists of a mixture of cyclopropane gas, C3H6, and oxygen gas, O2. If the mixture has a total pressure of 1.10 atm, and the partial pressure of the cyclopropane are 76.0 torr, what is the partial pressure of the oxygen in the anesthetic? A. 1.10 torr B. 11 torr C. 76 torr D. 752 torr E. 760 torr ANS: E The gas law, which is applied in pressure cookers or autoclaves, which gives the relationship between pressure and temperature at constant volume and amount of gas is A. Avogadro’s Law D. Charles’ Law B. Gay-Lussac’s Law E. Boyle’s Law C. Dalton’s Law Law ANS: B Which of the following does not equal the others? A. 1 mole of iron B. 55.85 grams of iron C. 6.02 x 1023 atoms of iron D. 1.00 gram of iron ANS: D Calculate the grams of SO2 gas present at STP in a 5.9 L container. A) 0.24 g B) 0.26 g C) 15 g D) 17 g E) 64 g ANS: D

A solution has the following label: The solute in this solution is A. sodium

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B. water Exam 2

Aqueous Sodium Nitrate 5.0%(m/v) NaNO3 C. NaNO3

D. aqueous

E. alcohol

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ANS: C 30. The solution described in question #29 contains A. 5.0 grams of NaNO3 in every 100 milliliters of solution B. 5.0 grams of NaNO3 in every 100 grams of solution C. 5.0 milliliters of NaNO3 in every 100 milliliters of solution D. 5.0 moles of NaNO3 in every 1.0 liter of solution E. 5.0 moles of NaNO3 in every 100 milliliters of solution ANS: A 31. Metallic iron reacts with oxygen gas to produce iron (III) oxide as follows: Fe + O2 2 Fe2O3 When the above reaction is balanced, what is the coefficient of oxygen? A. 1 B. 2 C. 3 D. 4 E. none of these ANS: C 32.

Which precipitate is formed in the reaction below? Refer to the solubility rules. CaCl2 (aq) + Na2CO3 (aq)  CaCO3 + 2 NaCl A. CaCl2

B. Na2CO3

C. CaCO3

D. NaCl

ANS: C

33.

If the theoretical yield of iron was 30.0 g and the actual yield was 25.0 g, calculate the per cent yield of iron from the equation: 2Al + Fe2O3 → Al2O3 + 2Fe ANSWER: % yield = (25.0/30.0) x 100 = 83.3%

34.

Calculate the molar mass of CaCO 3. ANS: 100.0 grams/mole

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Exam 2...