The formula for hydrated copper(ii) nitrate is cu(no3)2.xh2o. it contains 36.5% water crystallization by mass.

what is the value of x?

[ar= h: 1 ; n: 14; o: 16; cu: 64]

a) 4
b) 5
c) 6
d) 7

6

Explanation:

The percent mass is equal to the ratio between the mass of the component of interest and the total mass of the compound, multiplied by 100 % in case we need to express it as a percentage.

We may apply this knowledge to write the formula for copper(II) nitrate x-hydrate. Let's assume that we take 1 mole of the compound. Then we will divide x molar masses of water by the molar mass of the overall compound and multiply by 100 % to get the mass percent of water:

Here:

Substitute into the formula:

Solve for x:

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

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