Calculation Mol And Emperic

SeNsna/SmKsr/aLcUlatiON

Calculation

1.

2K(s) + Br2 (g) à 2KBr(s) How many moles of potassium are needed to react with 0.5 mole of bromine gas?how many KBr is produced ?

2. Ethene gas burns in excess oxygen according to the following equation. C2H4(g) + 3O2 (g) à 2C02 (g) + 2H20 (I) Find the volume of carbon dioxide released at STP if 42 g of ethene is burned completely.[Relative atomic mass: H, 1; C, 12. Molar volume: 22.4 dm3 mol -1 at STP].

3.

The equation below represents chemical reaction when Copper(II) carbonate is heated. CuCO3(s) à CuO(s) + CO2(g) (i) How many moles of copper(ll) carbonate must you use to produce 1 mole of copper(ll) oxide? [1 mark]

(ii)

Calculate the number of moles of copper(ll) carbonate needed to produce 1.6 g of copper(ll) oxide. [1 mark][Relative atomic mass: C, 12; O, 16; Cu, 64]

4. 0.24 g of Magnesium react with 0.16g of oxygen gas gas to form magnesium Element Mass Mole Ratio of mole Empirical formula oxide.Determine the empirical formula for this oxide ? 5. 2.44 g of antimony (Sb) combines with 0.48 g of oxygen to form an oxide. Determine the empirical formula of this oxide. (Relative atomic mass: O, 16 Sb, 122).

6. Silicon hydride contains 87.5% silicon by weight and the rest is hydrogen. Determine the empirical formula of silicon hydride. (Relative atomic mass: H, 1 Si, 28).

7. Reduction of 11.95 g of lead oxide yields of 10.35 g of lead metal. Determine the empirical formula of lead oxide. (Relative atomic mass: Pb, 207; 0, 16).

8.. The empirical formula for benzene is CH.. If its relative molecular mass is 78, what is it molecular formula ?