Question

4. Given the reaction: CH4 (8) + 2 O2(g) → CO2 (g) + 2 H20 (8) where AH = -891 kJ Calculate the enthalpy change if 1.00 g of methane (CH) is burned in excess oxygen.

Answer 1

55.69 joules

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Balanced Equation of combustion of metahne

$CH_{4}(g)+2O_{2}(g)\rightarrow CO_{2}(g)+2H_{2}O(g)$

combustion is exothermic.

Given that Enthalpy change for the combustion of Methane , $CH_{4}(g)+2O_{2}(g)\rightarrow CO_{2}(g)+2H_{2}O(g), \Delta H=-891j$

1 mole of Methane gas on combustion liberates 891 j of energy

1 mole of Methane = 16 g

$\Rightarrow$ 16 g of Methane gas on combustion gives out 891 j of energy.

1 g of Methane gas on combustion liberates how much energy( Enthalpy change)= ?

So, enthalpy change on combustion of 1 g of Methane gas =

  

891) 169

= 55.6875 joules.

= 55.69 joules

Entyalpy change on combusiton or burning of 1 g of Methane gas in excess of Oxygen = 55.69 jolues.

= 55.69 J