When 0.975 g of CaO is added to 200.0 mL of 0.500 M HCl(aq), a temperature increase of 400C is observed.
Assume the solution's final volume is 200.0 mL, the density is 1.00 g/mL, and the heat capacity is 4.184 J/gC.
Hrxn, for the reaction of
CaO(s) + 2H+(aq) Ca2+(aq) + H2O(l)
is______ kJ/mol.
The 400 C still bothers me. Could that be 40.0 C? Also, you need to learn (and quickly) to put arrows in the equation. Without arrows how are we to know which are reactants and which are products?
CaO (s) + 2H(aq) --->Ca2 (aq)+H20 (l)
it's 4.00 C. sorry about the earlier format
How much heat is transferred to the water?
q = massH2O x specific heatH2O x delta Tof H2O = ?? J
Then convert 0.975 g CaO to mols and divide to obtain J/mol. Convert that to kJ/mol.
To determine the enthalpy change of the reaction (ΔHrxn) in kJ/mol, we need to use the equation:
ΔHrxn = q / n
where:
q is the heat transferred in Joules (J),
n is the number of moles of the limiting reactant, and
ΔHrxn is the enthalpy change of the reaction in kJ/mol.
First, let's calculate the heat transferred (q) in Joules using the equation:
q = m × C × ΔT
where:
m is the mass of the solution in grams,
C is the specific heat capacity of the solution in J/g°C, and
ΔT is the temperature change in °C.
In this case, the mass of the solution can be calculated using the volume and density, so:
mass of the solution = volume × density
= 200.0 mL × 1.00 g/mL
= 200.0 g
Substituting the given values:
m = 200.0 g
C = 4.184 J/g°C
ΔT = 40 °C
Next, calculate the moles of the limiting reactant (CaO) using its molar mass:
moles of CaO = mass of CaO / molar mass of CaO
The molar mass of CaO (calcium oxide) can be found in the periodic table, which is approximately 56.08 g/mol.
moles of CaO = 0.975 g / 56.08 g/mol
Now that we have all the necessary values, we can calculate the heat transferred (q):
q = 200.0 g × 4.184 J/g°C × 40 °C
Finally, substitute the calculated values into the equation for ΔHrxn:
ΔHrxn = q / n
ΔHrxn = (q value calculated above) / (moles of CaO calculated above)
By solving this equation, you will obtain the enthalpy change of the reaction (ΔHrxn) in kJ/mol.