How much heat is liberated at constant pressure if .928 g of Fe reacts with 26.2 mL of .238 M HCl? Delta H = -87.9 kJ
To determine the amount of heat liberated in this reaction, we can use the equation:
q = m * C * ΔT
where:
- q represents the amount of heat energy released or absorbed
- m is the mass of the substance (in this case, Fe)
- C is the specific heat capacity of the substance (fe = 25.0 J/g·°C)
- ΔT is the change in temperature
First, let's calculate the moles of Fe by using its molar mass:
molar mass of Fe = 55.845 g/mol
moles of Fe = mass / molar mass
moles of Fe = 0.928 g / 55.845 g/mol
Next, we need to determine the moles of HCl used in the reaction. The balanced equation for this reaction is:
Fe + 2HCl -> FeCl2 + H2
From the balanced equation, we can see that the stoichiometric ratio between Fe and HCl is 1:2. Therefore, the moles of HCl used can be calculated as follows:
moles of HCl = (volume of HCl) * (molarity of HCl)
volume of HCl = 26.2 mL = 0.0262 L
molarity of HCl = 0.238 M
moles of HCl = 0.0262 L * 0.238 M * 2 (because of the stoichiometric ratio)
Now, to calculate the amount of heat liberated, we can use the equation:
q = n * ΔH
where:
- q is the amount of heat energy released or absorbed (in J)
- n is the number of moles of the limiting reactant (either Fe or HCl)
- ΔH is the enthalpy change for the reaction (given as -87.9 kJ)
Since Fe is the limiting reactant (because the stoichiometric ratio is 1:2), we will use the moles of Fe to calculate the heat liberated:
q = moles of Fe * ΔH
Finally, we can convert the heat from joules to kilojoules by dividing by 1000 (1 kJ = 1000 J).