The melting point of benzene (C6H6) is 5.5 oC and the heat of fusion at that temperature is 9.87 kJ/mol. How much heat would be required to melt 35.0 g of benzene at 5.5 oC?
Atomic weights: C 12.011 H 1.00794
mol benzene = grams/molar mass = ?
q(in J) = mols x 9870 J/mol = ?
6y
To calculate the heat required to melt 35.0 g of benzene at 5.5°C, we need to follow these steps:
Step 1: Calculate the number of moles of benzene.
First, we need to determine the molar mass of benzene (C6H6):
(6 * atomic mass of C) + (6 * atomic mass of H)
= (6 * 12.011 g/mol) + (6 * 1.00794 g/mol)
= 72.066 g/mol + 6.04764 g/mol
= 78.11364 g/mol
Next, we can calculate the number of moles using the given mass:
moles = mass / molar mass
= 35.0 g / 78.11364 g/mol
≈ 0.448 mol
Step 2: Calculate the heat required to melt the benzene.
The heat required can be calculated using the formula:
q = m * ΔHf
Where:
q = heat required (in joules)
m = mass (in grams)
ΔHf = heat of fusion (in joules/mol)
First, we need to convert the given heat of fusion from kJ/mol to J/mol:
9.87 kJ/mol = 9.87 * 1000 J/mol
= 9870 J/mol
Now we can calculate the heat required:
q = 35.0 g * 9870 J/mol
= 345450 J
Therefore, the heat required to melt 35.0 g of benzene at 5.5°C is approximately 345450 J.
To solve this problem, we need to use the formula:
Heat (q) = mass (m) × heat of fusion (ΔH)
First, we need to determine the number of moles of benzene present in 35.0 g. We can do this by using the formula:
Number of moles (n) = mass (m) / molar mass (M)
Molar mass of benzene (C6H6):
(6 × molar mass of carbon) + (6 × molar mass of hydrogen)
= (6 × 12.011 g/mol) + (6 × 1.00794 g/mol)
= 78.11388 g/mol
Number of Moles (n) = 35.0 g / 78.11388 g/mol
= 0.4480 mol
Now, we can calculate the heat required to melt 35.0 g of benzene using the equation:
Heat (q) = mass (m) × heat of fusion (ΔH)
where heat of fusion (ΔH) is given as 9.87 kJ/mol.
Heat (q) = 0.4480 mol × 9.87 kJ/mol
= 4.4144 kJ
Therefore, the amount of heat required to melt 35.0 g of benzene at 5.5 oC is 4.4144 kJ.