? asked in Science & MathematicsChemistry · 9 years ago

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.

1 Answer

  • John
    Lv 6
    9 years ago
    Favorite 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.

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