The volume of an unknown liquid is 15.0ml. the mass of the liquid and the graduated cylinder is 55.2g. if the mass of the graduated cylinder alone is 44.8g, what is the mass of the unknown liquid? round answer to 3 significant figures.

Mass of liquid unknown liquid =  10.4 g

Explanation:

Volume of liquid =  15 mL

Mass of liquid + graduated cylinder = 55.2 g

Mass of graduated cylinder = 44.8 g

Mass of unknown liquid = ?

Solution:

Mass of unknown liquid is calculated by subtracting the graduated cylinder mass from combined mass of liquid and graduated cylinder.

Mass of liquid = (Mass of liquid + graduated cylinder) - (Mass of graduated cylinder )

Mass of liquid =  55.2 g - 44.8 g

Mass of liquid =  10.4 g

So the mass of unknown liquid is 10.4 g.

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.