Question

(a) (i) LPG stands for liquefied petroleum gas. VArieties of LPG are marketed including a mixture fo propane (60%) and butane (40%) . If 10 litre of this mixture is burnt, find the total volume of carbon dioxide gas added to the atmosphere. Combustion reactions cab be represented as:
$C_3{H}_{8\left(g\right)}+{50}_{2\left(g\right)}\to 3C{O}_{2\left(g\right)}+4H_2{O}_{\left(g\right)}2C_4{H}_{10\left(g\right)}+13O_{2\left(g\right)}\to 8C{O}_{2\left(g\right)}+10H_2{O}_{\left(g\right)}$
(ii)
Calculate the percentage of nitrogen and oxygen in ammonium nitrate. [Relative molecular mass of ammonium nitrate is 80, H = 1, N = 14, O = 16].
(b)4.5 moles of calcium carbonate are reacted with dilute hydrochloric acid.
(i) Write the equation for the reaction .
(ii) What is the mass of 4.5 moles of calcium carbonate ? (Relative molecular mas of calcium carbonate is 100).
(iii) What is the volume of carbon dioxide liberated at STP?
(iv) What mass of calcium chloride is formed?
(Relative molecular mass of calcium chloride is 111).
(v) How many moles of HCl are used in this reaction?

Answer 1

(ii) % of $NinN{H}_{4}N{O}_3=28÷80\times 100$ =35%

% of O in $N{H}_{4}N{O}_3=48÷80$ x 100= 60%

(b) i) $CaC{O}_3\left(s\right)+2HCl\left(aq\right)\to CaC{l}_2\left(aq\right)+C{O}_2\left(g\right)+H_{2}O\left(l\right)$

ii) 1 mol of $CaC{O}_3$ = 100g

so the mass of 4.5 moles of $CaC{O}_3$ will be 4.5 x 100= 450g

iii) $CaC{O}_3\left(s\right)+2HCl\left(aq\right)\to CaC{l}_2\left(aq\right)+C{O}_2\left(g\right)+H_{2}O\left(l\right)$

1mole 2moles 1mole

molar volume of $C{O}_2$ at STP=22.4l

iv) relative molecular mass of $CaC{l}_2$=111g

if mass of 1mole of $CaC{l}_2$=111g

then 4.5 moles $CaC{l}_2$= 111x4.5x1= 499.5g

v) number of moles of HCl used=2