A. Helium in a balloon: an element B. Paint: a mixture
C. Tap water: a compound D. Mercury in a barometer; an element Question 2. Which answer includes all the following that are chemical changes and not physical changes?
I. freezing of water II. rusting of iron
III. dropping a piece of iron into hydrochloric acid (H2 is produced) IV. burning a piece of wood
V. emission of light by a kerosene oil lamp
A. III and IV B. II and V C. I, II, III, IV, and V D. II, III, IV, and V
Question 3. Which response lists all of the following properties of sulfur that are Physical properties and not other properties?
I. It reacts with hydrogen when heated.
II. It is a yellow solid at room temperature.
III. It is soluble in carbon disulfide.
IV. Its density is 2.97 g/cubic centimeter V. It melts at 1120C.
A. II, III, IV, and V B. II, IV, and V C. III, IV, and V D. II, III, and IV Question 4. The molecular mass of the compound, Al2(SO4)3 18H2O is:
A. 394.4 u B. 666.4 u C. 666.4 g D. 466.8 g Question 5. The molar mass of the compound, CuSO4.5H2O is:
A. 160 g B. 160 u C. 250 g D. 250 u Question 6. Which one of the samples contains the most atoms?
A. 1 mol of CO2(g) B. 1 mol of SF6(g) C. 1 mol of CH3COCH3(l) D. 1 mol of He(g) Question 7. Which one of the samples contains the most molecules?
A. 1 mol of CO2(g) B. 1 mol of UF6(g)
C. 1 mol of CH3COCH3(l) D. all contain the same number of molecules Question 8. Which of the following statements is(are) FALSE?
1. The percent by mass of each element in a compound depends on the amount of the compound.
2. The mass of each element in a compound depends on the amount of the compound.
3. The percent by mass of each element in a compound depends on the amount of element present in the compound.
A. 2 and 3 B. 1 only C. 1 and 2 D. 1, 2 and 3
Question 9. Analysis of a sample of a covalent compound showed that it contained 14.4% hydrogen and 85.6% carbon by mass. What is the empirical formula for the compound?
A. CH B. CH2 C. CH3 D. C2H3
Question 10. A compound contains, by mass, 40.0% carbon, 6.71% hydrogen, and 53.3% oxygen. A 0.320 mole sample of this compound weighs 28.8 g. The molecular formula of this compound is:
A. C2H4O2 B. C3H6O3 C. C2H4O D. CH2O Question 11. What mass of cerussite, PbCO3, would contain 35.0 grams of lead?
A. 27.1 g B. 45.1 g C. 42.4 g D. 35.6 g Question 12. Silicon carbide, an abrasive, is made by the reaction of silicon dioxide with graphite.
SiO2 +3C → SiC + 2CO
If 100 g of SiO2 and 100 g of C are reacted as far as possible, which one of the following statements will be correct?
A. 111 g of SiO2 will be left over. B. 44 g of SiO2 will be left over.
C. 82 g of C will be left over. D. 40 g of C will be left over.
Question 13. When 250. mL of a 0.15 M solution of ammonium sulfide (NH4)2S is poured into 120. mL of a 0.053 M solution of cadmium sulfate CdSO4, how many grams of a yellow precipitate of cadmium sulfide CdS are formed? The other product is
(NH4)2SO4. (Hint: Write out and balance the equation. Is this a limiting reagent problem?
A. 5.4 g B. 0.92 C. 2.6 g D. 1.9 g Question 14. What is the molarity of phosphoric acid in a solution labeled 20.0%
phosphoric acid (H3PO4) by weight with a density = 1.12 g/mL?
A. 0.98 M B. 2.3 M C. 2.7 M D. 3.0 M Question 15. How many grams of water are contained in 75.0 grams of a 6.10% aqueous solution of K3PO4?
A. 75.0 g B. 73.2 g C. 70.4 g D. 68.1 g Question 16. If 5.0 g of each reactant were used for the the following process,
the limiting reactant would be:
2KMnO4 +5Hg2Cl2 + 16HCl → 10HgCl2 + 2MnCl2 + 2KCl + 8H2O
A. KMnO4 B. HCl C. H2O D. Hg2Cl2
Question 17. The formation of ethyl alcohol (C2H5OH) by the fermentation of glucose (C6H12O6) may be represented by:
C6H12O6 → 2C2H5OH + 2CO2
If a particular glucose fermentation process is 87.0% efficient, how many grams of glucose would be required for the production of 51.0 g of ethyl alcohol (C2H5OH)?
A. 68.3 g B. 75.1 g C. 115 g D. 229 g Question 18. A commercially valuable paint and adhesive stripper, dimethyl sulfoxide (DMSO), (CH3)2SO, can be prepared by the reaction of oxygen with dimethyl sulfide, (CH3)2S, using a ratio of one mole oxygen to two moles of the sulfide:
If this process is 83% efficient, how many grams of DMSO could be produced from 65 g of dimethyl sulfide and excess O2?
A. 68 g B. 75 g C. 83 g D. 51 g Question 19. When 12 g of methanol (CH3OH) was treated with excess oxidizing agent (MnO4-
), 14 g of formic acid (HCOOH) was obtained. Using the following chemical equation, calculate the percent yield. (The reaction is much more complex than this;
please ignore the fact that the charges do not balance.) 3CH3OH + 4MnO4
-→ 3HCOOH + 4MnO2
A. 100% B. 92% C. 82% D. 70%
Question 20. Calcium carbide, CaC2, is an important preliminary chemical for industries producing synthetic fabrics and plastics. CaC2 may be produced by heating calcium oxide with coke: CaO + 3C→ CaC2 + CO
What is the amount of CaC2 which can be produced from the reaction of excess calcium oxide and 10.2 g of carbon? (Assume 100% efficiency of reaction for purposes of this problem.)
A. 18.1 g B. 28.4 g C. 20.8 g D. 19.8 g Question 21. Which of the following statements is FALSE for the chemical equation given below in which nitrogen gas reacts with hydrogen gas to form ammonia gas assuming the reaction goes to completion?
N2 + 3H2→ 2NH3
A. The reaction of one mole of H2 will produce 2/3 moles of NH3. B. One mole of N2 will produce two moles of NH3.
C. One molecule of nitrogen requires three molecules of hydrogen for complete reaction.
D. The reaction of three moles of hydrogen gas will produce 17 g of ammonia.
Question 22. When iron pyrite (FeS2) is heated in air, the process known as "roasting"
forms sulfur dioxide and iron(III) oxide. When the equation for this process is completed and balanced, using the smallest whole number coefficients, what is the coefficient for
"O2"?
___ FeS2 + ___ O2 → ___ SO2 + ___ Fe2O3
A. 2 B. 4 C. 7 D. 11 Question 23. What alkaline earth metal is located in period 3?
A. Li B. Na C. Ca D. Mg Question 24. Which of the following is a weak acid?
A. H2SO4 B. HClO3 C. HF D. HCl Question 25. How many following statements is TRUE?
(a) One mole of any acid will ionize completely in aqueous solution to produce one mole of H+ ions.
(b) Solutions of weak acids always have lower concentrations of H+ than solutions of strong acids ( If they are same molar concentration)
(c) The lower the concentration of H+ in an acidic solution, the higher the pH (d) All of the IA and IIA metal hydroxides are soluble.
(e) All weak acids are insoluble.
A. 1 B. 2 C. 3 D. 4 Question 26. Consider the following reaction:
NH3(g) + H2O(l) NH4+
(aq) + OH-(aq) Which of the following statements is false?
A. The double arrows indicate that ammonia, NH3, is only very slightly soluble in water.
B. The reaction is reversible.
C. When ammonia is added to water, NH4+
and OH- ions are produced in a 1:1 ratio.
D. When solutions of NH4Cl and NaOH are mixed, ammonia is produced.
Question 27. Which one of the following salts is insoluble?
A. NH4Cl B. Ca(NO3)2 C. BaCO3 D. Na2S Question 28. What salt is formed in the following acid/base reaction?
HClO3 + Ba(OH)2 →
A. BaCl2 B. BaClO3 C. H2O D. Ba(ClO3)2
Question 29. Which one of the following statements is FALSE?
A. For the reaction of a strong acid with a strong soluble base, the net ionic equation is always H+ + OH- → H2O
B. "Spectator ions" appear in the total ionic equation for a reaction, but not in the net ionic equation.
C. HF, HCl, and HNO3 are all examples of strong acids.
D. Titration is a process which can be used to determine the concentration of a solution.
Question 30. The spectator ion(s) in the following reaction is/are:
Na2CO3(aq) + Ba(NO3)2(aq) → BaCO3(s) + 2NaNO3(aq) A. Na+ and Ba2+
B. Ba2+ and CO32-
C. CO32-
and NO3-
D. Na+ and NO3-
Question 31. What is the net ionic equation for the acid-base reaction that occurs when acetic acid and potassium hydroxide solutions are mixed?
A. H+(aq) + OH-(aq) → H2O(l)
B. H+(aq) + KOH(s) → K+(aq) + H2O(l)
C. CH3COOH(aq) + KOH(s)→ KCH3COO(aq) + H2O(l) D. CH3COOH(aq) + OH-(aq) → CH3COO-(aq) + H2O(l)
Question 32. What is the net ionic equation for the acid-base reaction that occurs when nitric acid is added to copper(II) hydroxide?
A. H+(aq) + OH-(aq) → H2O(l)
B. 2H+(aq) + Cu(OH)2(s) → Cu2+(aq) + 2H2O(l) C. 2HNO3(aq) +Cu(OH)2(s) → Cu(NO3)2(s) + 2H2O(l) D. 2H+(aq) + 2NO3-
(aq) + Cu2+(aq) + 2OH-(aq) → Cu(NO3)2(s) + 2H2O(l)
Question 33. Which of the following statements is FALSE given the following net ionic equation?
H3PO4(aq) + 3OH-(aq) → PO43-(aq) + 3H2O(l)
A. If all the water evaporated away, the salt remaining could possibly be Na3PO4. B. The acid, H3PO4, is a weak electrolyte.
C. The base involved must be a strong soluble base.
Question 34. Which of the following statements is FALSE given the following net ionic equation?
2H+(aq) + Cu(OH)2(s)→ Cu2+(aq) + 2H2O(l)
D. If all the water evaporated away, the salt remaining could possibly be CuS.
B. The acid involved must be a strong electrolyte.
C. The base, Cu(OH)2, is an insoluble base.
D. This could possibly be the net ionic equation for HNO3 reacting with Cu(OH)2. Question 35. Consider the following reaction:
4NH3 + 5O2 → 4NO + 6H2O The element being oxidized and the oxidizing agent are:
A. N and NH3 B. N and O2
C. O and NH3 D. O and O2
II. PART 2 (3.0 points)
Exercise 1. 20.0cm3 of a metal hydroxide of concentration 0.06mol.dm–3 was titrated with 0.10 moldm–3 hydrochloric acid. It required 24.0 cm3 of the hydrochloric acid to exactly neutralise the metal hydroxide.
a. Calculate the number of moles of metal hydroxide used.
b. Calculate the number of moles of hydrochloric acid used.
c. What is the simplest mole ratio of metal hydroxide to hydrochloric acid?
d. Write a balanced equation for this reaction using your answers to parts a, b and c to help you. Use the symbol M for the metal.
e. Assume that the solution after the reaction contains 133.2 mg of solute. Let's define metal M
Exercise 2. 50cm3 of a gaseous hydride of phosphorus, PHn reacts with exactly 150cm3 of chlorine, Cl2, to form liquid phosphorus trichloride and 150 cm3 of hydrogen chloride gas, HCl.
a How many moles of chlorine react with 1 mole of the gaseous hydride?
b Identify the formula of the phosphorus hydride.
c Write a balanced equation for the reaction
Exercise 3. According to Vietnamese standards (TCVN 5709: 1993), carbon steel is classified based on carbon content as follows:
Steels High carbon steel Medium carbon steel
Low Carbon Steel Content
(% mass C)
< 1,80 < 1,2 < 0,22
Low carbon steel is used in the building materials industry. A steel sample that has just been produced, to be put into use for a suitable purpose, must go through a rigorous quality control process.
A sample of carbon steel (assuming only Fe and C) has a mass of 7.85 grams is added to concentrated HCl solution (density of D = 1.19 g/ml) in excess, in a conical flask. Above the flask, which is sealed with a rubber stopper, there is a sharp tube connected to a graduated syringe for measuring the volume of gas released. The reaction took place completely, the released gas was measured at a pressure of 1 bar and a temperature of 25oC. Observe for a while, see that the piston of the syringe moves a part to the specified position of 3.36 dm3, then stops moving. Given that 1 mole of gas at a pressure of 1 bar and a temperature of 25oC occupies a volume of 24.79 liters.
Please determine whether this steel sample is used in the field of construction materials?
Why?
ĐÁP ÁN ĐỀ ỔN TẬP SỐ 12 I. PART 1 (7.0 points)
Câu Đ/án Câu Đ/án Câu Đ/án Câu Đ/án
1 C 11 B 21 E 31 D
2 D 12 D 22 E 32 B
3 A 13 B 23 D 33 D
4 B 14 B 24 C 34 A
5 C 15 C 25 B 35 B
6 C 16 D 26 A
7 D 17 C 27 C
8 B 18 A 28 D
9 B 19 C 29 C
10 B 20 A 30 D
II. PART 2 (3.0 points) Exercise 1.
a) The number of moles of metal hydroxide used = 20.0 0.06 1.2 10 3 1000x x mol b) The number of moles of hydrochloric acid used = 24.0 0.1 2.4 10 3
1000x x mol c) The simplest mole ratio of metal hydroxide to hydrochloric acid =
3 3
1.2 10 1 2.4 10 2
x x
d) balanced equation for this reaction
M(OH)2 + 2 HCl → MCl2 + 2H2O 1.2x10-3 2.4x10-3 1.2x10-3
e) The solute in the after reaction is MCl2
According the above reaction, the number mole of MCl2 = 1.2x10-3 mol
→ The molar mass of MCl2 = 133.2 1 3 111 / 1000 x1.2 10 g mol
x
→ M + 35.5x2 = 111→ M = 40 ( Ca – Canxium) Exercise 2.
a) The simplest volume ratio of chlorine to phosphorus hydride = The simplest mole ratio of chlorine to phosphorus hydride 150 3
50 1
→ So 3 moles of chlorine react with 1 mole of the gaseous hydride b) The formula of the phosphorus hydride is PH3 ( hydrogen photphide) c) a balanced equation for the reaction
PH3 + 3Cl2 → PCl3 + 2HCl Exercise 3.
Mole of H2 releases = 3.36 0.13554
24.79 mol
We have reaction: Fe + 2HCl → FeCl2 + H2
0. 0.13554 mol ←0.13554 mol
According the above reaction, the number mole Fe = 0.13554 mol
→ mass of Fe in the 7.85 grams of steel = 0.13554 mol x56 =7.59 grams
→ mass of C in the 7.85 grams of steel = 7.85 – 7.59 = 0.26 grams The mass percent of C in the above sample steel is 0.26 100 3.31%
7.85x >0.22%
→ this steel sample is not used in the field of construction materials
ĐỀ ÔN TẬP SỐ 13 I. PART 1 (7.0 points)
Question 1. How can 0.1 g samples of the two white solids, lead(II) chloride and silver chloride, be distinguished from one another?
A. Add 10 mL of cold water to each. The silver chloride will dissolve.
B. Add 10 mL of hot water to each. The lead(II) chloride will dissolve.
C. Add 10 mL of sodium chloride to each solution. The lead(II) chloride will become warm and release chlorine gas.
D. Add 10 mL of zinc chloride solution to each. The silver chloride will change to metallic silver.
Question 2. What is the mass of one molecule of water in grams?
A. 18 B. 1.1 × 10-21 C. 3.0 × 10-23 D. 1.7 × 10-24 Question 3. If nitrogen atoms are represented as filled circles and and oxygen atoms as open circles, how much NO2 can be prepared from the mixture shown?
A.4 molecules B. 5 molecules C. 6 molecules D. 8 molecules Question 4. A mineral containing iron(II) sulfide but no other sulfides is treated with excess hydrochloric acid to produce hydrogen sulfide. If a 3.15 g sample of the mineral yields 448 mL of hydrogen sulfide gas (measured at 0 ˚C and 760 mm Hg), what is the mass percentage of iron(II) sulfide in the sample?
A. 20.4 B. 35.5 C. 55.8 D. 71.0
Question 5. What is the maximum mass (in grams) of NO that could be obtained from 15.5 g of N2O4 and 4.68 g of N2H4 when they react? The balanced chemical equation is 2N2O4 + N2H4 6NO + 2H2O.
A. 4.38 B. 5.04 C. 15.2 D. 26.2
Question 6. What volume of 0.108 M H2SO4 is required to neutralize 25.0 mL of 0.145 M KOH?
A. 16.8 mL B. 33.6 mL C. 37.2 mL D. 67.1 mL Question 7. All of the following are expected to affect the rate of an irreversible chemical reaction EXCEPT
A. adding a catalyst. B. removing some products.
C. increasing the temperature. D. decreasing the reactant concentration.
Question 8. The oxidation of ammonia produces nitrogen and water according to the equation:
4NH3(g) + 3O2(g) 2N2(g) + 6H2O(g)
If the rate of formation of N2 at a certain temperature is 3.0 mol.L-1.s -1, what is the rate of disappearance of O2?
A. 2.0 mol.L-1.s -1 B. 3.0 mol.L-1.s -1 C. 4.5 mol.L-1.s -1 D. 9.0 mol.L-1.s -1
Question 9. 2SO2(g) + O2(g) 2SO3(g) ∆H < 0 Which change(s) will increase the quantity of SO3(g) at equilibrium?
I. increasing the temperature
II. reducing the volume of the container III. adding He to increase the pressure
A. I only B. II only C. I and III only D. II and III only Question 10. ClO3-
+ Br– → Cl2 + Br2 Which is the reducing agent?
A. ClO3-
B. Br– C. Cl2 D. Br2
Question 11. When the atoms; Li, Be, B, Na, are arranged in order of increasing atomic radius which is the correct order?
A. Li, Be, B, Na B. Li, Na, B, Be C. Na, Li, Be, B D. B, Be, Li, Na
Question 12. Which element is a gas at 25 ˚C and 1 atm pressure?
A. chlorine B. phosphorus C. silicon D. bromine Question 13. How should a student prepare 100 mL of a 1.0 M H2SO4 solution from a 10. M H2SO4 solution?
A. Add 90 mL of H2O to 10 mL of 10 M H2SO4. B. Add 10 mL of 10 M H2SO4 to 90 mL of H2O.
C. Add 10 mL of 10 M H2SO4 to 80 mL of H2O, stir and dilute to 100 mL after allowing to cool.
D. Add 80 mL of H2O to 10 mL of 10 M H2SO4, stir and dilute to 100 mL after allowing to cool.
Question 14. For which compound are the empirical and molecular formulas the same?
A. C6H5COOH B. C6H4(COOH)2 C. HOOCCOOH D. CH3COOH Question 15. What volume of liquid A has the same mass as 80.0 cm3 of liquid B?
A. 40.0 cm3 B. 97.0 cm3 C. 160. cm3 D. 193 cm3 Question 16. How many water molecules are in a 0.10 g sample of CuSO4 . 5H2O (M = 249.7)?
A. 1.2 x 1021 B. 2.4 x 1021 C. 2.4 x 1022 D. 1.2 x 1023 Question 17. Acetylene, C2H2, reacts with O2 to produce CO2 and H2O. What is the O2/C2H2 ratio in the balanced equation?
Density (g/cm3 ) Liquid A 0.660 Liquid B 1.59
Question 18. A sample of oxygen gas and a sample of an unknown gas are weighed separately in the same evacuated flask. Use the data given to find the molar mass of the unknown gas (assume experiments are carried out at the same pressure and temperature).
A. 22 g/mol B. 38 g/mol C. 44 g/mol D. 84 g/mol Question 19. What is the most effective way to condense a gas?
A. Decrease the temperature and increase the pressure.
B. Decrease the temperature and decrease the pressure.
C. Increase the temperature and decrease the pressure.
D. Increase the temperature and increase the pressure.