During the combustion of 5.00 g of octane, C8H18, 239.5 kcal (1002 kJ) is released. How many kilocalories are released by the combustion of 19.7 g of C8H18 ?
See your other two problems. Don't get confused because you're talking about kJ and kcal. Rethink the problem as "you burn 5.00 pennies and get 239.5 dollars for doing that work. How many dollars can you get by burning 19.7 pennies?
To find out how many kilocalories are released by the combustion of 19.7 g of C8H18, we can set up a proportion using the given information:
5.00 g of octane releases 239.5 kcal (1002 kJ)
19.7 g of octane would release x kcal (unknown)
The proportion is given by:
5.00 g / 239.5 kcal = 19.7 g / x kcal
To find x, we can cross-multiply and solve for x:
5.00 g * x kcal = 19.7 g * 239.5 kcal
x kcal = (19.7 g * 239.5 kcal) / 5.00 g
x kcal = 9566.15 kcal
Therefore, the combustion of 19.7 g of C8H18 would release approximately 9566.15 kcal or 9,566 kcal.
To calculate the number of kilocalories released by the combustion of 19.7 g of C8H18, we can set up a proportion using the given values.
First, let's establish the relationship between the amount of octane burned and the energy released. We know that 5.00 g of octane releases 239.5 kcal.
Now, let's set up the proportion:
(5.00 g) / (239.5 kcal) = (19.7 g) / (x kcal)
To solve for x (the number of kilocalories released by the combustion of 19.7 g of C8H18), we can cross-multiply and solve for x:
5.00 g * x kcal = 19.7 g * 239.5 kcal
x = (19.7 g * 239.5 kcal) / 5.00 g
x ≈ 939.59 kcal
Therefore, the combustion of 19.7 g of C8H18 releases approximately 939.59 kilocalories.