When 10.0 g of KOH is added to 100.0 g water, the solution's temperature increases from (25.18 C) to (47.53 C). What is the molar enthalpy of solution for KOH?
i tryed
q=(m)x(c)x(delta T)
didn't really work. i got 22.35 J
do i use that to find the molar enthalpy if so how?
No, that's not what you obtained. I know it isn't. 22.35 = Tfinal - Tinitial = 47.53-25.18 = 22.35 and that doesn't come close to m x c x delta T.
haha, yep,
ok so q= 10,276.53 J
and to get the answer in molar enthalpy should i divide q by the mole of KOH
10.0g KOH (1 mol KOH/ 56.105g) = 0.1782 mol KOH
10,276.53 J / 0.1782 mol KOH = 57,668.5J/mol
= 57.6 kJ/mol
Is this right?
and would the answer be positive because the temperature is increased?
Close but no cigar.
You had better redo the q part. I think it's closer to 9300 J or so. The rest of it is as you have it. q/mols KOH = J/mol but it usually is reported in kJ/mol.
To find the molar enthalpy of solution for KOH, you need to use the equation:
q = m × c × ΔT
Where:
q = heat absorbed or released by the solution (in joules)
m = mass of the solution (in grams)
c = specific heat capacity of the solution (in J/g·°C)
ΔT = change in temperature of the solution (in °C)
In your case, the mass of the solution is the sum of the mass of KOH and the mass of water: 10.0 g + 100.0 g = 110.0 g. The specific heat capacity of water is approximately 4.18 J/g·°C.
So, let's plug in these values into the equation:
q = 110.0 g × 4.18 J/g·°C × (47.53 °C – 25.18 °C)
q = 110.0 g × 4.18 J/g·°C × 22.35 °C
q = 10,764.51 J
Now, to find the molar enthalpy of solution, you need to divide the heat absorbed or released by the number of moles of KOH.
To find the moles of KOH, use the given molar mass of KOH: 39.1 g/mol for K, 16.0 g/mol for O, and 1.0 g/mol for H. So, the molar mass of KOH is 39.1 + 16.0 + 1.0 = 56.1 g/mol.
moles of KOH = mass of KOH / molar mass of KOH
= 10.0 g / 56.1 g/mol
≈ 0.178 mol
Now, divide the heat absorbed or released (q) by the number of moles of KOH:
Molar enthalpy of solution = q / moles of KOH
= 10,764.51 J / 0.178 mol
≈ 60,470 J/mol
Therefore, the molar enthalpy of solution for KOH is approximately 60,470 J/mol.