Gasohol contains ethanol (C2H4OH)(l), which when burned reacts with oxygen to produce CO2(g) and H2O(g). How much heat is released when 12.5g of ethanol burns?

C2H5OH(l) + 3 O2(g) --> 2 CO2(g) + 3H2O(l)

Delta H = -1368kJ

12.5 x (1mol/46.0g) = .271 mol of ethanol

.271 x 1368 = 370

(randi did 1235 Delta H, not 1368)

how about the negative sign?

-371.7

To calculate the amount of heat released when 12.5g of ethanol burns, you'll need to follow these steps:

1. Convert the mass of ethanol (C2H5OH) from grams to moles. To do this, divide the mass (12.5g) by the molar mass of ethanol (46.07 g/mol):

12.5 g C2H5OH ÷ 46.07 g/mol = 0.27 moles C2H5OH

2. Use the balanced equation to determine the molar ratio between ethanol (C2H5OH) and the amount of heat released (ΔH). From the equation, you can see that the ratio is 1:1368 kJ:

1 mole C2H5OH : -1368 kJ

3. Multiply the moles of ethanol by the ΔH value to find the amount of heat released:

0.27 moles C2H5OH × -1368 kJ/mol = -369.36 kJ

Therefore, when 12.5g of ethanol burns, approximately -369.36 kJ of heat is released. Notice that the negative sign indicates that the reaction is exothermic, meaning heat is released.

You get 1368 kJ when 1 mole (46 g) is burned; how much will you get when you burn 12.5 g?

335.5kj

What Rght said