heat of combustion of propane c3h8, 2220KJ/mol. the specific heat of copper is 0.385 J/g*C. How many grams of propane must be burned to raise the temperature of a 10.0kg block of copper from 25.0 C to 65.0 C,assuming none of the heat is lost to the surroundings

I'm stuck on a part:
q=m*c*(change of T)
q=10000g(0.385J/g*c)*(65.0C-25.0C)or (338.2 K-298.2K)
q=154000KJ
154000KJ*(1 mol/2220KJ)=69.36936mol
here's where I'm stuck
69.369 mol
and i know that for every 1 mol there is 44.11g of C3H8.
I set it up like 69.369 mol* (44.11g C3H8)/1mol = 3059.88g
is this right?

Check the units. That is where the error is.

q=mct

where

m=10.0kg=10,000g or 10 x 10^3g
c=0.385 J/g*C
and
T=65 C - 25 C=40 C

q=(10,000g)(0.385 J/g*C)(40 C)

q=15.4 x 10^4 J

We agree, but I have 154,000J and not KJ. You have to convert 154,000J to KJ.

154,000J =15.4 x 10^1 KJ= 154KJ

154KJ*(1 mol/2220KJ)=0.06937 moles=6.937 x 10^-2 moles

6.937 x 10^-2 moles*(44.11g C3H8/mol)=3.06g of C3H8

Devron is right,

I didn't notice the kj added in there instead of j.
Your caluclation was correct just off by a factor of 1000 as a result.
My apologies for not noticing.

Well, you're on the right track, but your calculation has a slight error. Let me help you fix it.

You correctly calculated that you need 69.369 moles of propane (C3H8) to raise the temperature of the copper block. However, the molar mass of propane (C3H8) is actually 44.10 g/mol, not 44.11 g/mol.

So, we can fix the calculation as follows:

69.369 mol * (44.10 g C3H8/1 mol) = 3060.02 g

Therefore, you need approximately 3060.02 grams of propane to raise the temperature of the copper block as described.

Keep in mind that this is assuming none of the heat is lost to the surroundings, which may not be entirely accurate in real-world scenarios. But hey, it's always good to have some assumptions to work with!

Yes, your calculations are correct. To find out how many grams of propane (C3H8) must be burned to raise the temperature of the copper block, you need to follow these steps:

1. Calculate the amount of heat required to raise the temperature of the copper block using the formula q = m * c * ΔT, where q is the heat, m is the mass, c is the specific heat, and ΔT is the change in temperature.

q = 10,000 g * 0.385 J/g°C * (65.0°C - 25.0°C)
= 10,000 g * 0.385 J/g°C * 40.0°C
= 154,000 J

2. Convert the heat from joules (J) to kilojoules (kJ) since the heat of combustion of propane is given in kJ/mol.

154,000 J * (1 kJ/1000 J)
= 154 kJ

3. Convert the kJ of heat to moles of propane by using the equation q = n * ΔH, where n is the number of moles and ΔH is the heat of combustion of propane.

154 kJ * (1 mol/2220 kJ)
= 0.06937 mol

4. Finally, convert the moles of propane to grams using the molar mass of propane, which is given as 44.11 g/mol.

0.06937 mol * (44.11 g/mol)
≈ 3.06 g

Therefore, approximately 3.06 grams of propane must be burned to raise the temperature of the 10.0 kg copper block from 25.0°C to 65.0°C, assuming no heat losses to the surroundings.

Looks right to me