Calculate the Heat Absorbed?
6.84g of NaNO3 are placed into 288g of H2O and the temperature rises 12 degrees Celsius.
(a) the heat absorbed by the water
(b) the # of mol of salt used
(c) the heat of solution of the salt in J/mol and kJ/mol
Please help, I'm really unsure of what to do.
- JohnLv 69 years agoFavorite Answer
one equation you need is the famous
Q = m*c*delta T the eenergy is the product of the mass, the temp change, and the specific heat of the material being warmed up.
so, Q = 288 * 4.18 * 12 = 14446 joules = 14.446 kJ
one mole of sodium nitrate would have a mass of 85 grams (23 + 14 + 16 + 16 + 16)
1 gram os sodium nitrate represents one 85th of a mole
so 6.84 grams is 6.84 85ths of a mole
Now you need to imagine what the temperature rise would be if you used a mole of sodium nitrate.
Or better still, what energy would be given out if you dissolved a mole of NaNO3
To calculate it you need to divide the joules (or kilojoules) by the moles.
it's all there in the unit of the answer; kilojoules per mole.