The addition of hydrochloric acid to a silver nitrate solution precipitates silver chloride according to the reaction: agno3(aq)+hcl(aq)→agcl(s)+hno3(aq) when 50.0 ml of 0.100 m agno3 is combined with 50.0 ml of 0.100 m hcl in a coffee-cup calorimeter, the temperature changes from 23.40 ∘c to 24.21 ∘c. calculate δhrxn for the reaction as written. use 1.00 g/ml as the density of the solution and cs=4.18j/(g⋅∘c) as the specific heat capacity of the solution.

The change in reaction enthalpy is 49305.02 J / mol

C = 4.18

delta T = 24.25 - 23.16

= 1.09 mol

= 0.070L * 0.185M

= 0.01295 m

= d * v

= 1.00 * (0.070 + 0.070)

= 0.14g

= q / mol HCl

= [mC (deltaT)] / mol HCl

= (0.14 * 4.18 * 1.09) / (0.01295)

= 49.3 kJ

Molarity of solution = Moles of solute x 1000 / Volume of solution (in mL)

Molarity of HCl solution = 0.185 M

The volume of the solution = 70.0 mL

0.185 = Mole HCl x 1000 / 70.0

Mole HCl = 0.185 x 70.0 / 1000 = 0.01295mol

\ Delta H_ (rxn) = (q) (n)

Where,

q = amount of heat absorbed = 638.5 J

n = number of moles = 0.01295 moles

\ Delta H_ (rxn) = change in enthalpy of reaction

\ Delta H_ (rxn) = 638.5J / 0.01295mol = 49305.02J / mol

Therefore, the change in reaction enthalpy is 49305.02 J / mol

Enthalpy (H) is the chemical energy contained in a system. The enthalpy of a system cannot be measured, which can be measured is the change in enthalpy (ΔH) that accompanies the change in the system.

The standard enthalpy of formation is the heat absorbed or released in the formation of one mole of substances from the elements measured at 250C and 1 atmospheric pressure. A standard decomposition enthalpy is a heat absorbed or released in the decomposition of one mole of substances into its elements.

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Grade: Middle School

Subject: Chemistry

Keyword: Molarity, HCl, enthalpy

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

1. they vary with a higher number because boiling is way hotter than melting