The molar mass of an unknown salt is 63.5. If 4.81 g is added to 81.1 mL of water the temperature changes from 20.95oC to 21.62oC. What is the molar heat of solution (J/mol) of the salt? (Assume all of the heat is transfered to the water) Express your answer to the nearest whole number (XXXX.).

mass H2O x specific heat H2O x (Tfinal-Tinitial) = q

dHsoln/g is q/4.81
dHsoln/mol is (q/4.81)* 63.4g/mol

Thanks for all the help Bob!

To calculate the molar heat of solution, we need to use the formula:

q = m × c × ΔT

Where:
q = heat transferred to the solution (in Joules)
m = mass of the solution (in grams)
c = specific heat capacity of water (4.184 J/g·°C)
ΔT = change in temperature (in °C)

First, let's calculate the mass of the solution. We are given that 4.81 g of the unknown salt is added to 81.1 mL of water. However, we need to convert the volume of water to mass. The density of water is approximately 1 g/mL. Therefore:

Mass of water = volume of water × density of water
= 81.1 mL × 1 g/mL
= 81.1 g

Next, we can calculate the change in temperature:

ΔT = final temperature - initial temperature
= 21.62°C - 20.95°C
= 0.67°C

Now, we can substitute the values into the formula to find the heat transferred to the solution:

q = 4.81 g × 4.184 J/g·°C × 0.67°C
= 13.2158 J

Finally, to find the molar heat of solution, we need to determine the number of moles of the salt used. To do this, we can use the molar mass given (63.5 g/mol) and the mass of the salt used (4.81 g):

Number of moles = mass of salt / molar mass
= 4.81 g / 63.5 g/mol
= 0.0757 mol

Now, we can calculate the molar heat of solution:

Molar heat of solution = heat transferred to solution / number of moles
= 13.2158 J / 0.0757 mol
≈ 174 J/mol

Therefore, the molar heat of solution of the unknown salt is approximately 174 J/mol.