A cube of some rock weighs 6 grams, and a same-sized cube of water weighs 2 grams. What is the specific gravity of this rock?

The specific gravity of the rock with respect to water is equal to 3

Explanation:

To solve the question, we list out the variables as follows

Mass of rock = 6 grams

Mass of equal volume of water = 2 grams

Specific gravity or relative density is the mass of a unit volume of a substance divided by the mass of an equal volume of a reference material.

Specific gravity = (mass of substance)/(mass of equal volume of water)

Therefore the specific of the rock sample is = (mass of cube of rock sample)/(mass of same-sized cube of water)

= (6 grams)/(2 grams) = 3

The specific gravity of the rock = 3

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.