When 1.98 g of NaOH (molar mass= 40 g/mole) are added to 75.0 mL of a 0.350 M HCl solution in a coffee-cup calorimeter, the temperature changes from 21.7°C to 25.8°C. If the resulting solution has a mass of 78.2 grams and a specific heat capacity of 3.97 J/g°C, what is the enthalpy change (ΔHrxn) for this reaction in kJ/mole.

(ΔHrxn) = 1.273kJ/mol

Explanation:

Applying

m=78.2, c= 3.97, ∆t= 25.8-21.7

(ΔHrxn)= mc∆t

=78.2× 3.97× 4.1= 1.273kJ/mol

the electrical  conductivity  of asolution  of an electrolyte is measured by determining the resistance of thesolution  between two flat or cylindrical electrodes separated by a fixed distance.

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml