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2 years ago

If 1.48 g of Cl2 reacts with excess P, what is the total change in enthalpy in kilojoules? 2P+5Cl2⟶2PCl5ΔH=−886kJ

Chemistry

1 answer:

FinnZ [79.3K]2 years ago

3 0

Answer:

-3.72 (or -3.70 depending on what values you used)

Explanation:

First, use the molar mass of Cl2 convert the mass of Cl2 to moles.

1.48 g Cl2(1 mol70.906 g)=0.02087 mol Cl2

Note that we are given ΔH=−886kJ. This refers to the enthalpy change associated with the reaction of 5mol of Cl2 by the balanced equation shown below.

2P+5Cl2⟶2PCl5ΔH=−886kJ

Therefore, to determine the enthalpy change associated with the reaction of 1.48gCl2, divide ΔH by 5molCl2 to determine the enthalpy change per mole of Cl2, then multiply by 0.02087 mol Cl2. (note: if you round up here to .021 mol of Cl2 you will get the final answer of -3.72 later)

0.02087 mol Cl2(−886 kJ5 mol Cl2)=−3.698 kJ

Rounding the answer should to three significant figures, we find that the enthalpy change associated with the reaction of 1.48gCl2 is −3.70 kJ.

Notice that coefficients in stoichiometric equations (indicating numbers of moles) are exact, so they do not constrain the number of significant figures.

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C) It will take 1.37 years to remove all of the arsenic from the lake.

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