Question

Determine the heat given off to the surroundings when 9.0 g of aluminum (fm = 26.98) reacts according to the equation 2al + fe2o3 → al2o3 + 2fe, δh°rxn= –849 kj/mol

Answer 1

The heat given off to the surroundings when 9.0 g of aluminum reacts is 267 kJ.

Step-by-step explanation:

The heat given off to the surroundings can be determined by using the enthalpy change (ΔH) for the reaction and the amount of aluminum reacted.

Given that the enthalpy change (ΔH) for the reaction is -849 kJ/mol and the molar mass of aluminum (Al) is 26.98 g/mol, we can calculate the heat given off when 9.0 g of aluminum reacts:

Heat = (ΔH / molar mass) * mass of aluminum = (-849 kJ/mol / 26.98 g/mol) * 9.0 g = -267 kJ

Therefore, the heat given off to the surroundings when 9.0 g of aluminum reacts is 267 kJ.

Answer 2

Hey there!:

Number of moles:

Molar Mass Al = 26.98 g/mol

n = mass / molar mass

n = 9.0 / 26.98

n = 0.3336 moles of Al

Given the reaction :

2 Al + Fe2O3 = Al2O3 + 2 Fe

From the equation, 2 moles of Al give off 849 kJ of heat :

Actual heat given off :

0.3336 / 2 * 849 =

0.3336 / 1698 = 1.4*10² Kj

Hope that helps!