Consider the following equation:
4B(s) + 3O2 (g) → 2B2O3 (s)
ΔH = - 2509.1 kJ
How much heat (in kJ) is transferred when 989 mg of B2O3 (s) is formed?
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To find the amount of heat transferred when 989 mg of B2O3 (s) is formed, we can use the equation and the given enthalpy change (ΔH) value.
First, we need to convert the mass of B2O3 to moles. The molar mass of B2O3 is 69.62 g/mol.
Let's perform the conversion:
989 mg = 0.989 g
0.989 g * (1 mol/69.62 g) ≈ 0.01418 mol
Now, we can use the balanced equation to determine the molar ratio between B2O3 and heat transfer.
The equation shows that 2 moles of B2O3 are produced for every 4 moles of B(s) consumed.
Therefore, the molar ratio of B2O3 to heat transfer is 2: -2509.1 kJ.
Now, we can calculate the heat transfer:
0.01418 mol B2O3 * (-2509.1 kJ/2 mol B2O3) ≈ -17.82 kJ
Hence, the amount of heat transferred when 989 mg of B2O3 (s) is formed is approximately -17.82 kJ. The negative sign indicates that the reaction is exothermic, meaning heat is released.