When heated, calcium carbonate goes through a chemical reaction, and produces calcium oxide (quick lime) powder and carbon
dioxide gas. a chemist performed this reaction in a lab and found that the mass of the calcium oxide (quick lime) was less than the
mass of the calcium carbonate. what is the reason behind this decrease in mass?
a. the carbon dioxide molecules produced were unstable and lighter in mass.
b. calcium oxide crystals produced break up at room temperature, leading to the difference in
c. carbon dioxide is produced, and as a gas, it was not captured to measure its mass.
d.
the calcium oxide crystals produced were unstable and lighter in mass.
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Carbon dioxide is produced, and as a gas, it was not captured to measure its mass.

Explanation:

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.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.