I'm trying to relearn some trig for a math placement test to put me into a calculus class and am having trouble with one particular problem. One of the example problems is as follows:
Find cos^2(2x)+sin^2(2x)
I know the trig identity cos^2(x)+sin^2(x)=1 but I don't know how to apply this...
Awesome, that helped a lot, thank you :approve:. I think I've got this idea on lock-down.
The only problem left with this question for me was that when I looked up the answer it was 5.52 g, instead of my calculated 6.11. Which, if I calculated the energy needed to heat the water 61 degrees...
Well that makes more sense, thanks! I think I've partially got an understanding. From Wikipedia, the heat of combustion is 802 kJ/mol or 50,125 J/g
I'm not 100% sure on how to use the equation you gave me, -qCH4 = n(CH4) * ΔH(comb)
if that means -306,268.8 J / -50,125 J/g = n(CH4) then...
Homework Statement
How many grams of methane (CH4 (g)) must be combusted to heat 1,200 grams of water from 26.0 degrees Celsius to 87.0 degrees Celsius, assuming water is in liquid state as a product and 100% efficiency in heat transfer?
Given data:
mass of H2O = 1.20 kg
specific heat...