(b) If 3.8 kcal (16 kJ) is released by combustion of each gram of glucose, how m

Question

(b) If 3.8 kcal (16 kJ) is released by combustion of each gram of glucose, how many kilocalories are released by the combustion of 1.50 mol of glucose? How many kilojoules? (c) What is the minimum amount of energy (in kJ) a plant must absorb to produce 15.0 g of glucose? 7.30 (During the combustion of 5.00 g of octane, C8H18, 239.5 kcal (1002 kJ) is released. (a) Write a balanced equation for the combustion reaction. (b) What is the sign of /t for this reaction? (c) How much energy (in kJ) is released by the combustion of 1.00 mol of C&H18;? (d) How many grams and how many moles of octane must be burned to release 450.0 kcal? (e) How many kilojoules are released by the combustion of 17.0 g of CsgHi8?

Explanation / Answer

Balanced equation:
2 C8H18(g) + 25 O2(g) ===> 16 CO2(g) + 18 H2O(g)
Reaction type: Combustion

Question b

Since it is exothermic reaction H symbol will be negtive which means energy is released.

Question C

Heat energy realesed for 5 gm of octane = 1002 kJ

Molar mass of Octane =  114.228 g/mol

heat realsed for 1 mole octane = 1002 x 114.23 / 5 = 22891 kJ

Question d

Heat in calories released for 5 gm octane = 239.5 Kcal

amount of octane realesed for 450 Kcal = 5 x 450 /239.5 = 9.39 gm

Moles of octane = 9.39 / 114.22 = 0.0822 Moles

Question e

Heat energy realesed for 5 gm of octane = 1002 kJ

Amout of heat realsed for 17g octane = 1002 x 17 / 5 = 3406.8 kJ

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