Experiment #1 (Known Reaction 1 above) Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) will be carried out using calorimetry. A certain mass of Mg will be added to a certain volume of HCl. The AQUEOUS solution of HCl is very DILUTE so we will consider it WATER for our calculations.Once the Mg is placed in the HCl the t1 will be taken and once the reaction is over (the temperature stops changing) the t2 will be taken. Watch this video link for Experiment 1 and enter the data into the observation table. (4 marks) Mass of Mg 0.50 g Mass of HCl (mL=g) 100 g t1 22 oC t2 45 oC *** Remember HCl is going to be considered H2O CALCULATIONS FOR EXPERIMENT #1 Use the data above and calculate the molar enthalpy (ΔHx) of the reaction in terms of Mg. HINT you need to do the 2 steps for this calculation ΔH = mcΔt & ΔH = nΔHx and this answer will be your ΔH value for your KNOWN equation #1. The video mentions figuring out the Limiting Reagent but it is Mg that you are calculating in terms of. (6 marks) t2-t1=ΔH → 45-22=23
Question
Experiment #1 (Known Reaction 1 above) Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) will be carried out using calorimetry. A certain mass of Mg will be added to a certain volume of HCl. The AQUEOUS solution of HCl is very DILUTE so we will consider it WATER for our calculations.Once the Mg is placed in the HCl the t1 will be taken and once the reaction is over (the temperature stops changing) the t2 will be taken. Watch this video link for Experiment 1 and enter the data into the observation table.
(4 marks)
Mass of Mg
0.50 g
Mass of HCl (mL=g)
100 g
t1
22 oC
t2
45 oC
*** Remember HCl is going to be considered H2O
CALCULATIONS FOR EXPERIMENT #1
Use the data above and calculate the molar enthalpy (ΔHx) of the reaction in terms of Mg. HINT you need to do the 2 steps for this calculation ΔH = mcΔt & ΔH = nΔHx and this answer will be your ΔH value for your KNOWN equation #1. The video mentions figuring out the Limiting Reagent but it is Mg that you are calculating in terms of.
(6 marks)
t2-t1=ΔH → 45-22=23
Solution
First, we need to calculate the heat change (q) using the formula q = mcΔt.
Here, m = mass of HCl = 100g (since we are considering HCl as H2O, we use the mass of HCl) c = specific heat capacity of water = 4.18 J/g°C (since we are considering HCl as H2O, we use the specific heat capacity of water) Δt = change in temperature = t2 - t1 = 45°C - 22°C = 23°C
Substituting these values into the formula, we get:
q = 100g * 4.18 J/g°C * 23°C = 9614 J
Next, we need to calculate the number of moles of Mg. The molar mass of Mg is approximately 24.31 g/mol.
So, number of moles of Mg = mass of Mg / molar mass of Mg = 0.50g / 24.31 g/mol = 0.0206 mol
Finally, we can calculate the molar enthalpy (ΔHx) of the reaction using the formula ΔHx = q / n, where n is the number of moles.
So, ΔHx = 9614 J / 0.0206 mol = 466,699 J/mol or 466.7 kJ/mol
Therefore, the molar enthalpy of the reaction in terms of Mg is 466.7 kJ/mol.
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