In a constant‑pressure calorimeter, 55.0 ml of 0.940 m h 2 so 4 was added to 55.0 ml of 0.370 m naoh . the reaction caused the temperature of the solution to rise from 21.65 ∘ c to 24.17 ∘ c. if the solution has the same density and specific heat as water ( 1.00 g / ml and 4.184 j / ( g ⋅ °c), respectively), what is δ h for this reaction (per mole of h 2 o produced)? assume that the total volume is the sum of the individual volumes.

ΔH = -57 kJ/mol (negative because it's an exothermic reaction)

Explanation:

Step 1: Data given

55.0 mL of 0.940 M H 2 SO 4 was added to 55.0 mL of 0.370 M NaOH

temperature of the solution to rise from 21.65 ∘ C to 24.17 ∘ C.

Density = 1g/mL

Specific heat = 4.184 J/g°C

Step 2: The balanced equation

H2SO4 + 2NaOH → Na2SO4 + 2H2O

Step 3: Calculate mass of the volume

55.0 mL + 55.0 mL = 110.0 mL

Mass = volume * density

Mass = 110 mL * 1g/mL

Mass = 110 grams

Step 4: Calculate moles of H2SO4

Moles H2SO4 = Molarity * volume

Moles H2SO4 = 0.940 M * 0.055 L = 0.0517 moles H2SO4

Step 5: Calculate moles NaOH

Moles NaOH = 0.370 M * 0.055 L

Moles NaOH = 0.02035 moles

Step 6: The limiting reactant

For 1 mol H2SO4, we need 2 moles NaOH to produce 1 mol of Na2SO4 and 2 moles of H2O

NaOH is the limiting reactant. It will completely be consumed (0.02035 moles).

H2SO4 is in excess. There will be reacted 0.02035/2 = 0.010175 moles

There will remain 0.0517 - 0.010175 = 0.041525 moles

Step 6: Calculate the heat

Q = m*c*ΔT

⇒ with m = the mass of solution = 110 grams

⇒ with c= the specific heat = 4.184 J/g°C

⇒ with ΔT = T2- T1 = 24.17 - 21.65 = 2.52 °C

Q = 110g * 4.184 J/g°C * 2.52 °C

Q = 1159.8 J

Step 7: Calculate moles H2O

Moles NaOH consumed = moles H2O produced

Moles H2O produced = 0.02035 mol

Step 8: Calculate ΔH

ΔH = 1159.8 / 0.02035

ΔH = 56992.6 J/ mol = 57 kJ/mol

since this is an exothermic reaction, ΔH is negative: -57 kJ/mol

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current