PART 1 (7.0 points) Question 1. Consider the following differences between Hydrogen and Helium gases

Question 4. Aqueous solutions of which of the following pairs of compounds will not

I. PART 1 (7.0 points) Question 1. Consider the following differences between Hydrogen and Helium gases

1. While Helium is a non-flammable gas, Hydrogen is a flammable gas 2. Helium is lighter than Hydrogen gas

Which of the above statements is/are correct?

A. 1 Only B. 2 Only C. Both 1 & 2 D. Neither 1 nor 2 Question 2. Highest percentage of nitrogen is found in which among the following fertilizers among the given options?

A. Calcium ammonium nitrate B. Ammonium nitrate C. Calcium nitrate D. Urea

Question 3. Potassium permanganate is used to purify water. Which among the following properties of Potassium permanganate helps in this work?

A. sterilizing B. oxidizing C. reducing D. leaching Question 4. Which among the following is known as Quick Lime?

A. CaO B. CaCO2 C. Ca(OH)2 D. CaCl2

Note: Ca(OH)2: Slakedlime Ca(OH)2: limewater

Question 5. Which of the following is an alkaline earth metal?

A. Pottasium B. Lead C. Copper D. Calcium Question 6. Which among the following is responsible for depletion of Ozone?

A. Carbon monoxide B. Carbon dioxide C. Chlorofluoro carbon D. Mercuric oxide

Question 7. Which among the following is an example of a Chemical Change?

A. Rusting of iron B. Magnetisation of iron C. Melting of iron D. Heating of iron

Question 8. In a sample of pure water, only one of the following statements

is always true at all conditions of temperature and pressure. Which one is always true?

A. [H3O+] = 1.0 x 10-7 M B. [OH-] = 1.0 x 10-7 M C. pH = 7.0 D. [H3O+] = [OH-]

Question 9. The [H+] in a 0.050 M solution of Ba(OH)2 is:

A. 1.0 x 10-5 M B. 5.0 x 10-2 M C. 1.0 x 10-13 M D. 5.0 x 10-10 M Question 10. Which of the following solutions has the lowest pH at 25oC? (No calculations required.)

A. 0.2 M sodium hydroxide B. 0.2 M hypochlorous acid C. 0.2 M ammonia D. 0.2 M bromhydric acid Question 11. Which metal can be found as the free element?

A. Na B. Mn C. Fe D. Pt

Question 12. A reaction sequence for the reduction of one of the iron ores is as follows:

2 C(coke) + O2 → 2 CO Fe2O3 + 3 CO → 2 Fe + 3 CO2

Calculate the amount of coke necessary to produce 800 g of Fe ( Known that, efficiency of the reaction is 75%)

A. 114 g B. 1030 g C. 258 g D. 172 g Question 13. What is the charge on the copper ion in the mineral azurite,

Cu3(CO3)2(OH)2?

A. 2+ B. 1+ C. 0 D. 1- Question 14. Which of the following is NOT true for the Group 1A elements ( except H element) ?

A. Most of them are soft, silvery corrosive metals.

B. Their atomic radii increases with increasing molecular weight.

C. They are named the alkaline earth metals.

D. They are excellent conductors of heat and electricity.

Question 15. Which element group is the most reactive of all the metallic elements?

A. alkali metals B. alkaline earth metals

C. coinage metals D. transition metals Question 16. Of the following oxides, the most basic is:

A. MgO. B. Na2O. C. P2O3. D. SO2. Question 17. The most abundant metal in the earth's crust is:

A. Cu B. Fe C. Na D. Al Question 18. What is the major mineral present in phosphate rock?

A. Ca3(PO4)2 B. Na2HPO4 C. Ca10(PO4)6F2 D. NaH2PO4

Question 19. Which compound gives photochemical smog a brownish color?

A. NO B. HNO2 C. NO2 D. N2O4

Question 20. Which of the following does not correctly describe ammonia?

A. pyramidal molecule B. polar molecule C. extremely soluble in water D. none of these

Question 21. What maximum mass of sulfuric acid can be produced from the sulfur contained in 100 kilograms of iron pyrite that is 75.0% FeS2?

A. 84.4 kg B. 123 kg C. 136 kg D. 144 kg Question 22. What maximum mass of sulfuric acid can be produced from the sulfur contained in 100 kilograms of iron pyrite that is 75.0% FeS2?

A. 84.4 kg B. 123 kg C. 136 kg D. 144 kg Question 23. Which of the following statements about sulfuric acid is false?

A. It is a strong acid.

B. One mole of sulfuric acid reacts completely with two moles of potassium hydroxide.

C. During the dilution of sulfuric acid, the correct method is to add water to sulfuric acid.

D. It is often present in acid rain and sulfuric acid is used as acid in batteries Question 24. Chlorine gas is prepared commercially by:

A. electrolysis of carbon tetrachloride. B. oxidation of chloride ion with F2(g).

C. electrolysis of NaCl(aq). D. oxidation of chloride ion with Br2(aq).

Question 25. Which of the following substances is the strongest reducing agent?

A. Cl2 B. Cl-

C. Br2 D. Br-

Question 26. Which of the following is NOT true for the halogens?

A. They are nonmetals.

B. They show the -1 oxidation number in most of their compounds.

C. Elemental halogens exist as diatomic molecules.

D. The electronic configuration of their outermost electrons is ns2 np6. Question 27. What makes carbon such a unique element?

A. Elemental carbon comes in two forms, diamond and graphite.

B. Carbon forms four bonds, although the ground state configuration would predict the formation of fewer bonds.

C. Carbon forms covalent bonds rather than ionic bonds.

D. Difference any other element, carbon can bond to itself to form straight chains, branched chains and rings.

Question 28. Hydrated copper sulphate, also known as bluestone with the chemical formula CuSO4.5H2O, is often used as an antiseptic, fungicide, herbicide and insecticide... When heated CuSO4.5H2O gradually loses mass. The following graph shows the decrease in mass of CuSO4.5H2O with increasing temperature.

The nearest composition of the solid after the temperature reaches 2000C is

A. CuSO4.H2O B. CuSO4.4H2O C. CuSO4 D. CuO Question 29. A vial containing Na2SO3 solution (X solution) for a long time. The concentration of Na2SO3 in solution X was determined again as follows

- Experiment 1: Adding 10ml of Y solution consisting of 0.5M BaCl2 and 2.5M HCl to 5ml of X solution, 0.233 grams of white precipitate was obtained.

Experiment 2: Slowly add bromine water solution to 5ml of X solution until the solution has a stable light yellow color, add 10ml of Y solution, 0.699 grams of white precipitate was obtained. What is the concentration of Na2SO3 in solution X?

A. 0,2M B. 0,4M C. 0,6 M D. 0,8M Question 30. Complete pyrolysis of a mixture of solids X including Cu(NO3)2 and AgNO3. The obtained gas mixture was waded through cold water to obtain Y solution and 168 ml of colorless gas Z (at STP). Let Y react with a sufficient amount of NaOH solution to obtain a solution containing 9.35 grams of one salt. The mass percent of AgNO3 in the mixture X is

A. 42,86% B. 40,41% C. 57,56% D. 57,14%

Question 31. NH3 is an important reagent in the chemical industry, produced by the Haber-Bosch method, using a direct reaction between N2 and H2.

At the condition that the molar ratio between N2 and H2 is 1:3, the temperature is 4500C the pressure is 200 atm, the iron powder catalyst, the NH3 synthesis reaction gives an yield of about 25%.

Which of the following statements is not true about NH3 synthesis?

A. Lowering the temperature, the rate of NH3 synthesis decreases B. Increasing the temperature the yield of NH3 synthesis increases C. Increasing the pressure the yield of NH3 synthesis increases D. Iron catalyst will increase the rate of ammonia synthesis

Question 32. An atom of element X has an electron configuration of 1s22s22p63s1. Which of the following properties of element X is not true?

A. In its pure form, X reacts with water to produce hydrogen gas.

B. The compound of X with chlorine is an ionic compound.

C. Atom X readily accepts an extra electron to form a stable 3s2 shell configuration.

D. Compounds of X with oxygen are soluble in water to form a basic solution.

Question 33. Complete combustion of 6.20 an organic compound A requires a sufficient amount of O2 (dktc) to obtain a mixture of combustion products. Lead all the combustion product into the container of Ba(OH)2 solution, 19.7 grams of precipitate appeared and the mass of solution decreased by 5.5 grams. Filter out the precipitate, heat the filtrate to obtain 9.85 grams of precipitate. The molecular formula of A is

A. C2H4O2 B. C2H6O C. C2H6O2 D. C3H8O Question 34. What is the sum of all coefficients when the following net ionic equation is balanced using the smallest whole number coefficients possible? Do not forget

coefficients of one.

2MnO4-

+ 3Mn2+ 4OH- → 5MnO2 + 2H2O (in basic solution)

A. 19 B. 16 C. 13 D. 11 Question 35. When the system A + B C + D is at equilibrium,

A. the sum of the concentrations of A and B must equal the sum of the concentrations of C and D.

B. the forward reaction has stopped.

C. both the forward and the reverse reactions have stopped.

D. neither the forward nor the reverse reaction has stopped.

II. PART 2 (3.0 points)

Exercise 1. In power plants, the burning of coal produces SO2 because the coal contains a small amount of sulfur (hence sulfur is also burned). One way to remove SO2 from the flue gases of power plants is to react it with an aqueous solution of H2S. One product of this reaction is sulfur and the other is water.

(a) How many moles of SO2 will be produced by burning 1.00 ton (1.00 ×103 kg) of coal

(b) Write a balanced chemical equation for the reaction between SO2 and H2S.

(c) What are the oxidation states of sulfur in SO2 and H2S?

(d) At 25 ˚C and 100 kPa, how many liters of hydrogen sulfide (H2S) gas would be needed to remove all the SO2 formed in (a)? ( known that 100kPa = 0,987atm)

(e) If the untreated flue gases of power plants are released into the environment, SO2 will react with another pollutant, NO2, to produce sulfur trioxide and nitrogen monoxide.

Write the reaction take place between SO2 and NO2.

(g) When SO3 dissolves in atmospheric water, we get acid rain! Write a balanced chemical equation for the reaction of SO3 with water.

Exercise 2. An alkaline earth metal (1.00 g) is reacted with chlorine gas to produce the resulting chloride salt (1.81 g). A solution of the salt in water gives a red flame test.

Identify the alkaline earth metal and give the chemical formula for the chloride salt.

Exercise 3. Phosphorus and compounds of this element account for the second highest concentration in the human body. A compound that is considered the main mineral component of tooth enamel, ivory and bone has the molecular formula Ca5(PO4)3(OH) (hydroxyapatite). In dentistry, this compound is coated with a metal layer (titanium - an anti-rust alloy) to facilitate implantation into the tooth. This substance in powder form is used to fill in bone voids caused by accidental fractures, facilitating natural bone

remodeling. Hydroxyapatite is prepared by dissolving phosphoric acid in an excess dilute calcium hydroxide solution

1. Write the chemical equation that occurs.

2. Calculate the mass of hydroxyapatite prepared from 100kg of 85% phosphoric acid solution when reacting with excess calcium hydroxide solution, the efficiency reaches 90%

3. To help strengthen tooth enamel and prevent tooth decay, F- ions are added to bottled water at a concentration of 1.0 mg F- ions per 1 liter of water. In toothpastes, the F- ion is added in small amounts in the form of sodium fluoride (NaF) salt.

According to a 2013 Harvard study, children living in areas with fluorinated water had lower IQs on average than in other areas. The F- ion is toxic to the nervous system. With the amount: 0.2 grams of F- can be dangerous to people weighing 70kg

3.1. If a student weighs about 70kg, use water containing F- with the amount of 1mg/1 L of water to help strengthen tooth enamel and prevent tooth decay. If the average volume of water this student drinks in a day is 2 L, does the amount of F- affect health?

3. 2. According to the American Dental Association, an adult should take 3mg of F- daily in the form of NaF to prevent tooth decay. The amount of NaF is not toxic to the body when it is below 3.19.10-2 grams / 1 kg of body. If a sample of toothpaste contains 0.28%

NaF, how many grams can a person weighing 75kg swallow without affecting health?

Đề ôn tập số 6

I. PART 1 (7.0 points)

II. PART 2 (3.0 points) Exercise 1.

(a) How many moles of SO2 will be produced by burning 1.00 ton (1.00 ×103 kg) of coal containing 3.00% sulfur by mass?

Mass of sulfur is 1x103 x3% = 30 kg

Mol of sulfur = mol of SO2 30x103 : 32 = 937.5 moles

(b) Write a balanced chemical equation for the reaction between SO2 and H2S.

SO2(g) + 2H2S(aq)  3S(s) + 2H2O(l)

(c) What are the oxidation states of sulfur in SO2 and H2S?

S in SO2: +4 S in H2S: -2

(d) At 25 ˚C and 100 kPa, how many liters of hydrogen sulfide (H2S) gas would be needed to remove all the SO2 formed in (a)? ( known that 100kPa = 0,987atm)

Moles of hydrogen sulfide (H2S) gas would be needed to remove all the SO2 formed in (a):

2x 937.5 = 1875 moles

Volume of hydrogen sulfide at 250C and 100KPa: 1875 x 0.082 x (25+273) : 0.987 = 46420.973L

(e) If the untreated flue gases of power plants are released into the environment, SO2 will react with another pollutant, NO2, to produce sulfur trioxide and nitrogen monoxide.

Write the reaction take place between SO2 and NO2. SO2 (g)

+ NO2(g)  SO3(g)

+ NO(g)

(g) When SO3 dissolves in atmospheric water, we get acid rain! Write a balanced chemical equation for the reaction of SO3 with water.

SO3(g)

+ H2O(l)  H2SO4(aq)

Exercise 2. Suppose that earth metal is M M + Cl2  MCl2

Mass off chlorine is reacted : 1.81 – 1 = 0.81 g

Câu Đ/án Câu Đ/án Câu Đ/án Câu Đ/án

1 A 11 D 21 B 31 B

2 D 12 D 22 B 32 C

3 B 13 A 23 C 33 C

4 A 14 C 24 C 34 C

5 D 15 A 25 D 35 D

6 C 16 B 26 D

7 A 17 D 27 D

8 D 18 A 28 A

9 C 19 C 29 B

10 D 20 D 30 B

 M is Sr ( Strontium)

 formula for the chloride salt is: SrCl2 ( Strontium chloride) Exercise 3.

1. Write the chemical equation that occurs.

3H3PO4 + 5Ca(OH)2  Ca5(PO4)3(OH) + 9H2O

2. Calculate the mass of hydroxyapatite prepared from 100kg of 85% phosphoric acid solution when reacting with excess calcium hydroxide solution, the efficiency reaches 90%

Mass of H3PO4 = 100 x 85% = 85kg Mole of H3PO4 = 85 x 103: 98

Mole of Ca5(PO4)3(OH) : 85 x 103: 98:3 x 90%

Mass of Ca5(PO4)3(OH) : 85 x 103: 98:3 x 90% x 502 =130.662x103 g = 130.622 kg 3.1. Mass of F- in 2L of water is: 2x 1 = 2mg = 0.002 g <0,2 g  the amount of F- in 2L of water dosen‘t affect this student‘s health

3. 2. The maximum of NaF a person weighing 75kg swallow without affecting health is 75x 3.19.10-2 /1 = 2.3925 g

The mass of toothpaste contains 0.28% NaF is

2.3925: 0.28% = 854.46 g

ĐỀ ÔN TẬP SỐ 7 I. PART 1: (7.0 marks)

Question 1. Which metal reacts most vigorously with water?

A. Ca B. K C. Mg D. Na

Question 2. Which substance produces an acidic solution when it is bubbled into water?

A. CO2 B. Ar C. NH3 D. CH4

Question 3. Which substance is the least soluble in H2O?

A. K2CO3 B. KHCO3 C. Ca(HCO3)2 D. CaCO3

Question 4.Which separation technique is based on differences in the volatility of the substances to be separated?

A. filtration B. distillation

C. solvent extraction D. paper chromatography

Question 5. If 1.50 g of H2C2O4.2H2O were heated to drive off the water of hydration, how much anhydrous H2C2O4 would remain?

A. 0.34 g B. 0.92 g C. 1.07 g D. 1.50 g

Question 6. People use sand to make metal molds. To thoroughly clean the sand particles on the metal surface after casting, what solution should we use?

A. NaOH dilution solution B. Dilute solution of H2SO4 C. HF solution. D. HCl solution

Question 7. A colorless solution is known to contain one of these ions. Which ion is present if adding dilute HCl produces a white precipitate that dissolves when the solution is warmed?

A. Ag+ B. Cu2+ C. Hg22+

D. Pb2+

Question 8. The reaction of ethanol, C2H5OH, with oxygen is a popular classroom demonstration. Balance the equation to find the number of moles of gaseous products formed per mole of ethanol.

___C2H5OH(g)+ ___O2 (g) →___CO2 (g)+ ___H2O(g) A. 2 B. 3 C. 4 D. 5 Question 9. Ammonia is produced in accordance with this reaction diagram.

N2(g)+ H2(g) → NH3(g)

In a particular experiment, 0.25 mol of NH3 is formed when 0.5 mol of N2 is reacted with 0.5 mol of H2 . What is the percent yield?

A. 75% B. 50% C. 33% D. 25%

Question 10. Which gas is least suitable for collection over water?

A. Ar B. O2 C. CO2 D. NH3

Question 11. The mass of 560 cm3 of a gas at 0 ˚C and 1 atm is 1.60 g. Which gas could it be?

A. O2 B. CO2 C. SO2 D. Cl2

Question 12. One of the steps in the manufacture of nitric acid is the oxidation of ammonia shown in this equation.

4NH3 (g)+ 5O2 (g) →4NO(g)+ 6H2O(g)

If gaseous water appears at a rate of 0.025 molãmin–1, at what rate does ammonia disappear?

A. 0.0040 molãmin –1 B. 0.017 molãmin–1 C. 0.038 molãmin–1 D. 0.150 molãmin–1

Question 13. Which equation represents an oxidation-reduction reaction?

A. H2SO4+ 2NH3→ (NH4)2SO4 B. H2SO4+ Na2CO3→Na2SO4+ H2O + CO2

C. 2K2CrO4+ H2SO4→ K2Cr2O7+ K2SO4+ H2O D. 2H2SO4+ Cu →CuSO4+ 2H2O + SO2

Question 14. Which of these elements has the greatest electronegativity?

A. Br B. N C. O D. S

Question 15. Which oxide produces the most acidic solution when 0.1 mol is added to 1 L of H2O?

A. BaO B. CO2 C. SO2 D. SO3

Question 16. How many isomers have the molecular formula C5H12? A. 1 B. 2 C. 3 D. 5

Question 17. Which element reacts most rapidly with water at 25 °C to produce a gas?

A. aluminum B. carbon C. lithium D. phosphorus Question 18. Which pair of substances can be combined to produce ammonia gas?

1.(NH4)2SO4(s)and NaOH(aq) 2. NH3(aq) and HCl(aq) A. 1only B. 2only C. both1 and2 D. neither1 nor2

Question 19. What products result when equal volumes of equimolar aqueous solutions of copper(II)sulfate and barium hydroxide are mixed?

A. Ba2+(aq) , Cu2+(aq) , OH–(aq) , and SO4

2–(aq) B. Cu(OH)(s), Ba2+(aq) , and SO42–

(aq)

C. BaSO4(s), Cu2+(aq) , and OH–(aq) D. BaSO4(s)and Cu(OH)2(s)

Question 20. A heterogeneous system is produced when 0.040 moles of solid NaCl is added to 0.10 L of 0.10 M Pb(NO3)2. Which ion is present in the aqueous phase at the highest concentration?

A. Cl– B. NO3– C. Pb2+ D. Na+

Question 21. Which 50-mL container would be most suitable for measuring and dispensing 37 mL of an aqueous solution

A. B. C. D.

Question 22. H2C2O4(aq) + MnO4

–(aq) + H+(aq)  Mn2+(aq) + CO2(g)+ H2O(l) Oxalic acid, H2C2O4, reacts with permanganate ion according to the equation above.

How many mL of 0.0154 M KMnO4 solution are required to react with 25.0 mL of 0.0208 M H2C2O4 solution?

A. 13.5 mL B. 18.5 mL C. 33.8 mL D. 84.4 Ml Question 23. In the lab, what method do you use to collect NH3?

A. Collection by downward delivery B. Collection over water C. Collection by upward delivery D. All three can be used

Question 24. What is the correct order when the substances O2, H2O, OF2, and H2O2are arranged in order of increasing oxidation number for oxygen?

A. O2, H2O, OF2, H2O2 B. H2O, H2O2, O2, OF2 C. H2O2, O2, H2O, OF2 D. OF2, O2, H2O2, H2O

Question 25. Solubility of X solid in water vs. temperature graph is given below. When we heat 300 grams saturated solution at 15 0C to 35 0C, we known that 0.6 mol X is crystallized. The molar mass (grams/mole) of X is

A. 80 B. 36.5 C. 100 D. 64 Question 26. How many hydrogen atoms are in one molecule of propene?

A. 3 B. 4 C. 6 D. 8 Question 27. What bonds are present in H- C C- H ?

A. 5 sigma B. 4 sigma and 1 pi C. 2 sigma and 3 pi D. 3 sigma and 2 pi

Question 28. A 7.66 g sample of hydrated sodium sulfate, Na2SO4.xH2O, forms 4.06 g of anhydrous Na2SO4. What is the value of x?

A. 0.2 B. 3.6 C. 5 D. 7 Question 29. For the reaction, 2SO2(g)+ O2(g)  2SO3(g) ∆H˚< 0

Which change(s) will increase the fraction of SO3(g) in the equilibrium mixture?

1. Increasing the pressure 2. Increasing the temperature 3. Adding a catalyst

A. 1 only B. 3 only C. 1 and 3 only D. 1, 2 and 3 Question 30. MnO4-+ NO2-+ H+  Mn2++ NO3-+ H2O

When this equation is balanced correctly with the smallest integer coefficients, what is the coefficient for H+?

Question 31. Which species is nonpolar?

A. HCl B. OCl2 C. NCl3 D. CCl4

Question 32. the ‗lead‘ in a pencil is made of a mixture of graphite and clay. When the percentage of graphite is increased, the pencil slides across the paper more easily. Which statementbexplains this observation?

A. Graphite has a high melting point B. Graphite is a form of carbon C. Graphite is a lubricant D. Graphite is a non-metal

Question 33. How many different structural isomers exist for dichloropropane, C3H6Cl2? A. 4 B. 5 C. 6 D. some other number Question 34. All of the formulas below correspond to stable compounds EXCEPT A. CH2O B. CH2O2 C. CH3O D. CH4O Question 35. Which of the compounds shown are isomers?

1. CH3CH2OCH3 2. CH3CH2OCH2CH3 3. CH3CH2CH2OH 4. CH2=CHOCH3 A. 1 and 3 B. 1 and 2 C. 2 and 3 D. 1 and 4

II. PART 2: (3.0 marks)

Exercise 1. Dendritic crystals of silver are formed when copper metal is added to a solution of silver nitrate (AgNO3). The copper metal forms Cu2+ ions and displaces silver from solution.

Write two balanced ionic half-equations and a redox equation for the reaction between copper metal and a silver nitrate solution.

Exercise 2. A 4.0 L bottle of bleach contains 4.5% NaOCl (4.5 g NaOCl per 100 mL bleach). The bleach is prepared from sodium hydroxide and chlorine gas:

__NaOH(aq) + __Cl2(gas)  __NaCl(aq) + ___NaClO(aq)+ __H2O (l) a) Balance the reaction equation above.

b) Calculate the concentration of NaOCl in the bottle of bleach. Report your answer in mol/L.

c) Calculate the minimum mass of NaOH required to make 4.0 L of bleach.

Exercise 3. DDT, an insecticide harmful to fish, birds, and humans, is produced by the following reaction:

C6H5Cl + C2HOCl3  C14H9Cl5 + H2O chlorobenzene chloral DDT

In a government lab, 1142 g of chlorobenzene is reacted with 485 g of chloral.

a. Which reactant is limiting?

b. What mass of DDT is formed if H = 100%?

c. If the actual yield of DDT is 200.0 g, what is the percent yield?