If the heat of combustion for a specific compound is -1170.0 kJ/mol and its molar mass is 42.75 g/mol, how many grams of this compound must you burn to release 191.90 kJ of heat?

1170.0 kJ/42.75 x #g = 191.9 kJ

To solve this problem, we need to use the given heat of combustion (-1170.0 kJ/mol) and the molar mass (42.75 g/mol) to find the heat released per gram of the compound.

First, we can find the heat released per mole of the compound:
-1170.0 kJ/mol

Then, we can find the heat released per gram of the compound using the molar mass:
-1170.0 kJ/mol / 42.75 g/mol = -27.37 kJ/g

Next, we can calculate the grams of the compound required to release 191.90 kJ of heat:
grams = heat released / heat released per gram
grams = 191.90 kJ / -27.37 kJ/g

Now, let's perform the calculation:
grams = -191.90 kJ / 27.37 kJ/g
grams ≈ -7.02 g

The negative sign indicates that the reaction is exothermic, releasing heat. Therefore, you would need to burn approximately 7.02 grams of this compound to release 191.90 kJ of heat.