On a day wilderness expedition you'll need to heat of water to the boiling point each day. the air temperature will average . you have available canisters of compressed propane fuel, which you'll burn to heat the water. each canister has of propane in it. what is the minimum number of fuel canisters you must bring? the standard heat of formation of propane at is . you'll probably find other data in the aleks data resource.

36

Your question is not complere. but maybe it is like:

5 day expedition.

you'll need to heat 4.0kg

Air Temperature: 25 °C

each canister has 75 g

The standar heat of formation of propane at 25°C is −103.85 / kJmol...

If the data is not exactly the same, you can follow the same steps.

Explanation:

Given:

Weight of water = 4.0 kg = 4000 g

Boiling point  = 100 °C (T2)

Initial T ° Water= 25 °C (T1)

Specific heat capacity water (Cs) = 4.184 J / g°C

Then  

Energy (q) = m x Cs x (T2-T1)

q = 4000 g x  4.184 J / g°C x (100-25) °C

q = 1255200 J per day

For 5 days the amount of energy will be 5xq = 6276000 J = 6276 kJ

Then we know that the standard heat of formation of propane at 25°C is −103.85kJ/mol. Also, Molecular Weight propane= 44,1 g / mol

Then we can know how much propane it's needed:

Mass= 6276 kJ÷103.85 kJ / mol = 60.43 mol

Mass of propane= 60.43 mol ×  44,1 g/mol = 2664.9 g  

So, if each canister has 75.g of propane:  

Number of canister=  2664.9 g ÷ 75.g = 35.53 = 36 canisters