[schan1]

When 3.75g of sodium hydroxide (NaOH) was dissolved in 50g of water a value of 10.0oC was obtained for ?T.

Calculate the heat (calories) produced by the solution of 3.75 g of NaOH.


Additional information:

The molarity of  this solution of NaOH is 1.88M.

From my lab manual, 1 M of NaOH has a specific heat of .95 cal/g.C

so I converted to get the specific heat for 1.88M of NaOH:

1.88M * .95 cal/g.C / 1M = 1.786 cal/g.C

Total mass of NaOH solution is 53.75g

Therefore I used the equation of

q = s. m. ?T.

q = 1.786 cal/g.c * 53.75g * 10c = 960 cal

The capa set said this is not the right answer and I have no more ideas on how to solve it.... plz help me out....

[sdekivit]

it's the water that takes up the heat

--> thus when a heat change of 10 degrees is measured the heat taken up by the solution is:

Q = 4180 * 50 x 10^-3 * 10 = 2090 J = 500 cal

that's what i would say, but i'm ill so no guarantee the answer is correct.

[corky7]

Here's what you do:

it's an exothermic reaction - so:

q=grams of h2o * specific heat of H2O * change in temp

you get the answer in joules. you'll need to convert it to calories: q * .239cals/joule