Homework for the weekend

TOPIK: CHEMICAL FORMULAE AND

               EQUATION

1. The equation below represents the   reaction to extract aluminium from aluminium oxide.

             2Al₃O₃   →  4Al  +  3O₂

      What is the mass of aluminium that can be extracted from 102 g of  aluminium oxide?

      [Relative atomic mass: O, 16 ; Al, 27]

1. 13.5 g                          C.  54.0 g
2. 27.0 g                          D.  108.0 g

4.          XCO₃    →   XO  +  CO₂

The equation above shows the action of heat on the carbonate salt of metal X.

How many moles of XCO₃ are needed to produce 4.0 g of oxide X?

[Relative atomic mass: C, 12; O, 16; X, 64]

1. 0.03                             C.  0.08
2. 0.05                             D.  0.09

5.. What is the number of molecules in 1  mole of ammonia, NH₃?

      [Avogadro’s constant: 6.0 x 10²³ mol^-1]

A.    1.5 x 10²³ molecules

B.     6.0 x 10²³ molecules

C.    1.2 x 10²⁴ molecules

D.    2.4 x 10²⁴ molecules

6. A compound with the formula X₂CO₃ has a relative formula mass of 138.

    What is the relative atomic mass of X?

     [Relative atomic mass: C=12, O=16]

1. 39                                C.  78
2. 69                                D.  110

7. The table shows the mass of elements M  and O in an oxide, and the relative  atomic mass  of elements M and O.

Element	M	O
Mass/g	5.6	2.4
Relative atomic mass	56	16

 The empirical formula for oxide M is

1. M₂O₃                           C.  MO₂
2. M₂O                            D.  MO

8. 5 g of element X reacted with 8  of element Y to form a compound with the formula XY₂

      What is the relative atomic mass of element X?

      [Relative atomic mass of Y=80]

A.    25                                C.  50

B.     40                                D.  100

9. Which of the following statement is true for one mole of a substance?

A.    1 mol of copper contains 6.02 x 10²³ molecules

B.     1 mol of oxygen gas contains 6.02 x 10²³ atoms

C.    1 mol of water contains the same number of atoms as in 12g of carbon-12

D.    1 mol of carbon dioxide contains the same number of molecules as the number of atoms in 12g of carbon-12

10. Table below shows two elements and their respective relative atomic mass.

      The letters used are not the actual symbol of  the elements.

Element	Relative atomic mass
X	24
M	12

      Which of  the following is true about the atoms of elements X and M?

A.    The mass of 1 mol of X is twice the mass of 1 mol of M

B.     1 mol of X has the same mass as 1 mol of M

C.       The mass of an atom of X is 24 g and the mass of an atom of M is 12 g

D.     The number of mole in 12 g of atom X is equal to the number of mole in 12 g of atom M.

11. A balloon contains 6.02 x 10²³ of gas particles. What is the number of moles

     of the gas in the balloon?

     A  0.5 mol               C  3.0 mol

     B  1.0 mol               D  6.0 mol

12. One mole of a substance is defined as the quantity of a substance that contains the same number of particles in m g of element Y.  What are m and Y?

	m	Y
A	2	Hydrogen - 1
B	12	Carbon - 12
C	14	Nitrogen - 14
D	16	Oxygen - 16

13. When 6.4 g oxide of M reacted completely with hydrogen gas, 4.48 g of metal M is produced. What is the empirical formula of the oxide?

      [Relative atomic mass:O,16; M,56]

A MO                     C M₂O

B MO₂                    D M₂O₃

14. Which of the following gases contains 0.4 mol of atoms at room temperature and pressure?

[1 mol of gas occupies the volume of 24 dm³at room temperature and pressure]

A  4.8 dm³ He       C  4.8 dm³ SO₃

B  4.8 dm³ H₂        D  4.8 dm³ CO₂  

15. The following equation shows the decomposition reaction of copper(II) carbonate when heated at room temperature and pressure.

      CuCO₃  →  CuO  +  CO₂

Which of the following is not true when 1 mol of copper(II) carbonate is decomposed?

[Relative atomic mass: C = 12, O=16, Cu = 64 and 1 mol of gas occupies the volume of 24 dm³ at room temperature and pressure.]

A 1 mol of copper(II) oxide is formed

B 1 molecule of carbon dioxide gas is

    given off

C 80 g of copper(II) oxide is formed

D 24 dm³ of carbon dioxide gas is given off   

16. Which of the following contains 6.02 x 10²³ atoms?

A 1 mol of nitrogen gas

B 1 mol of chlorine gas

C 1 mol of ammonia gas

D 1 mol of neon gas

 17. What is the number of moles of copper(II) nitrates in 56.4 g of copper(II) nitrate, Cu(NO₃)₂?

[Relative atomic mass: O=16, Cu=64, N=14]

A  0.30 mol             C  0.45 mol

B  0.32 mol             D  3.33 mol

  

18. Sodium reacts with chlorine to form sodium chloride.

            2Na  +  Cl₂  →  2NaCl

19.  What is the mass of sodium chloride formed when 2.30 g of sodium reacts with excess chlorine?

[Relative atomic mass: Na=23, Cl=35.5]

A 2.93g           C 9.40g

B 5.85g           D 11.70g

20. The relative molecular mass of M₂(SO₄)₃ is 342. What is the relative atomic mass of element M?

[Relative atomic mass: O=16, S=32]

A 27                C 118

B 53                D 123

21. A sample of iron oxide contains 5.6 g of iron and 2.4 g of oxygen. What is the empirical formula of this compound?

[Relative atomic mass: O=16, Fe=56]

A Fe₂O₃           C FeO₂

B Fe₃O₄           D FeO

22. What is the minimum mass of zinc required to react with excess hydrochloric acid to produce 240 cm³ of hydrogen gas at room conditions?

[Molar volume of gas = 24 dm³ mol^-1 at room conditions;

Relative atomic mass: Zn = 65]

A 0.33 g          C 1.30 g

B 0.65 g          D 6.50 g

END OF QUESTIONS

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