Question

Calorimetry. Specific Heat of a Metal and Heat of Reaction 4. When 25.0 mL of 1.00 M sodium hydroxide, NaOH(aq) is added to 25.0 mL of 1.00 M sulfuric acid, H,SO, (aq), at 22.3°C, the temperature rises to 31.2°C. Assume the solution is sufficiently dilute, so its specific heat is 4.184 J/gºC and its density is 1.00 g/ml. a. Write the balanced chemical equation for the reaction of sulfuric acid with sodium hydroxide. b. Calculate and colution (Assume C = 21.0J/°C.), c. Calculate action in joules. d. Calculate AH in kJ/mole of acid.

Answer 1

a) For question 4, the balanced reaction between NaOH and H₂SO₄ will be

2 NaOH (aq) + H₂SO₄ (aq) $\rightarrow$ Na₂SO₄ (aq) + 2 H₂O (l)

b) The q_cal will be calculated by formula

q_cal = C_cal . $\Delta$ T

The $\Delta$ T for reaction is given by formula $\Delta$ T = (T_final - T_initial)

$\Delta$T = (31.2 - 22.3) = 8.9 ^oC.

Therefore q_cal = 21.0 J / ^oC * 8.9 ^oC = 186.9 J = 187 J

Since q_solution = m.c.$\Delta$T

Since mass of solution will be find by formula density = mass / volume.

Mass of solution = 25 + 25 = 50 ml

1.00 g / ml = m / 50 ml

Multiply both side by 50 ml.

Therefore 1.00 g / ml * 50 ml = m

m = 50g

q_solution = 50 g * 4.184 J / g ^oC * 8.9 ^oC = 1861.88 J = 1860 J

c) Since q for reaction will be -1861.88 J because heat absorbed by solution will be equal to heat lost by reaction and this heat lost will be negative. Therefore heat of reaction (q_reaction) is -1861.88 J or -1860 J.

d) Since $\Delta$ H_reaction = (q_reaction / number of moles)

To find $\Delta$ H_reaction first we need to find moles of acid by using formula molarity = moles / volume in litre.

Volume of H₂SO₄ = 25 ml * (1L / 1000 ml) = 0.025 L

Therefore rearranging formula of molarity for moles

moles = Molarity * volume in liter. Since M = moles / L. Therefore

moles = 1.00 moles / L * 0.025 L = 0.025 mol H₂SO₄.

For 0.025 mol we have q_reaction -1861.88 J. For finding out for one mole we need to divide this value by 0.025.

Therefore, $\Delta$ H_reaction = -1861.88 J / 0.025 mol = -74475.2 J / mol

By using dimensional analysis

-74475.2 J / mol * (1kJ / 1000 J) = -74.4752 kJ / mol.

After rounding off the answer will be -74.5 kJ / mol.

In multiple question we have to solve only one question. If you find any mistake please mention in comment box.

Thanks.