When 5.0g of CaCl2 was dissolved in 50 ml of water in a coffee cup calorimeter, the temperature of the solution rose from 22.3C to 30.5C. What is the qsoultion in J and what is the qrxn in J?

What is the deltaH in kJ/mol of CaCl2 dissolved?

I assume 50 mL H2O weighs 50 g.

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

Then q/gram = q/5 and delta H = (q/5) x (molar mass CaCl2) and convert that to kJ.
Remember that if the T increases then the heat from the rxn is exothermic and that makes delta H negataive.

To find the qsolution and qrxn, we need to use the equation:

q = m * c * ΔT

Where:
q is the heat transferred (in J)
m is the mass of the solution (in g)
c is the specific heat capacity of water (which we will assume to be 4.18 J/g°C)
ΔT is the change in temperature (final temperature - initial temperature)

Let's calculate qsolution first:

m = 50 ml of water
Since 1 ml of water has a density of approximately 1 g/ml, the mass of water is 50 g

ΔT = 30.5°C - 22.3°C = 8.2°C

q_solution = 50 g * 4.18 J/g°C * 8.2°C

Calculating this value, we get:
q_solution = 1709 J

Now let's calculate qrxn using the equation:

qrxn = -qsolution

Since heat is transferred from the surroundings to the system (the solution), the value of qrxn is the negative of qsolution:

qrxn = -1709 J

Now, to find the ΔH (enthalpy change) in kJ/mol of CaCl2 dissolved, we need to convert qrxn into kJ and divide it by the number of moles of CaCl2:

ΔH = qrxn / (moles of CaCl2)

First, let's calculate the moles of CaCl2:

molar mass of CaCl2 = 40.08 g/mol (Ca) + 2 * 35.45 g/mol (2 Cl)
molar mass of CaCl2 = 110.98 g/mol

moles of CaCl2 = 5.0 g / 110.98 g/mol

Calculating this value, we find:
moles of CaCl2 = 0.045 moles

Now, let's convert qrxn into kJ:
qrxn_kJ = qrxn / 1000

qrxn_kJ = -1709 J / 1000

Calculating this value, we get:
qrxn_kJ = -1.709 kJ

Finally, we can find the ΔH by dividing qrxn_kJ by the moles of CaCl2:

ΔH = qrxn_kJ / moles of CaCl2

ΔH = -1.709 kJ / 0.045 moles

Calculating this value, the ΔH is:
ΔH = -38 kJ/mol (rounded to the nearest whole number)