Question

Can someone help me by giving me the formula of determining the amount of energy used in a reaction?

Answer 1

Q=mc(deltaT)
Q is the amount of energy which you are looking for
M is the mass which you can find
C is the specific heat of water which is 4.18 J/gC
DeltaT is the change in temperature which you can find.

To find the mass, first you must know that the density of water is 1g/mL, meaning that 200 mL has a mass of 200 g. This means that to find the total mass (m in the equation) all you need to do is add the mass of water and NaOH.

200 g + 2.535 g=202.535 g.

To find deltaT you would need to take the final temperature minus the initial temperature.

27.8C-24.2C=3.6C

Then these values can be substituted into the equation:

q=(202.635g)(4.18J/gC)(3.6C)
Q=3049.25 J

Technically this should be rounded off to 1 significant figure (200 mL only had 1), but ignoring signficiant figure rules this should be correct. Also, sometimes other units like calories or kJ may be asked for, meaning that a conversion or alternate c value would be used.