Calculate the change in enthalpy for the reaction. (Use 1.0 g/mL as the density of the solution and 4.18 J/(g⋅∘C) as the specific heat capacity.) Express the enthalpy change in kilojoules per mole to two significant figures. ΔHrxn = nothing kJ/mol

Here is the full question

Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin plastic divider. When the divider is broken, the ammonium nitrate dissolves according to the following endothermic reaction: NH4NO3(s)→NH+4(aq)+NO−3(aq) In order to measure the enthalpy change for this reaction, 1.25 g of NH4NO3 is dissolved in enough water to make 25.0 mL of solution. The initial temperature is 25.8 ∘C and the final temperature (after the solid dissolves) is 21.9 ∘C. Part A Calculate the change in enthalpy for the reaction in kilojoules per mole. (Use 1.0g/mL as the density of the solution and 4.18J/g⋅∘C as the specific heat capacity.) Express your answer to two significant figures and include the appropriate units. ΔHrxn =   ??? kJ/mol

26 kJ / mol

Explanation:

Given that;

The mass of NH₄NO₃ = 1.25 g

Number of moles of NH₄NO₃ = Mass of NH₄NO₃ / Molar Mass of NH₄NO₃

Number of moles of NH₄NO₃= 1.25 g / 80.043 g/mol

Number of moles of NH₄NO₃= 0.016 mol

Volume of solution = 25.0 mL

Density of Solution = 1.0g/mL

Since;

Mass of Solution = Density x Volume

= 1.0g/mL × 25.0mL

= 25 g

Heat Generated (Q)  =

Q= 25g × 4.18 J/g°C x (25.8°C - 21.9°C)

Q =  407.55 J

Q = 407 × 10 ⁻³ kJ

Q = 0.40755 kJ

Δ =

=  

= 25.47 kJ/ mol

~ 26 kJ / mol

Therefore, the change in enthalpy for the reaction in kilojoules per mole = 26 kJ / mol

to make a supersaturated solution, make a saturated solution of sugar by adding 360 grams of sugar to 100 ml of water at 80 degrees celsius. when the water cools back down to 25 degrees, that 360 grams of sugar will still be dissolved even though the water should only dissolve 210 grams of sugar.