How much energy (in joules) is released when 0.06 kilograms of mercury is condensed to a liquid at the same temperature? A. 17,705.1 J B. 20,075.04 J C. 51,302.88 J D. 697.08 J

PLEASE HELP!!!!!

1 Answer
Jun 12, 2018

The answer is A

Explanation:

Begin the dimensional analysis by writing the given amount of mercury over 1:

(0.06" kg of Hg")/1

Multiply by the conversion factor from kilograms to grams:

(0.06" kg of Hg")/1(1000" g of Hg")/(1" kg of Hg")

Cancel the units:

(0.06cancel(" kg of Hg"))/1(1000" g of Hg")/(1cancel(" kg of Hg"))

Multiply by the mass to moles conversion factor for mercury:

(0.06cancel(" kg of Hg"))/1(1000" g of Hg")/(1cancel(" kg of Hg"))(1" mol of Hg")/(200.59" g of Hg")

Cancel the units:

(0.06cancel(" kg of Hg"))/1(1000cancel(" g of Hg"))/(1cancel(" kg of Hg"))(1" mol of Hg")/(200.59cancel(" g of Hg"))

Multiply by the heat of vaporization factor for mercury :

(0.06cancel(" kg of Hg"))/1(1000cancel(" g of Hg"))/(1cancel(" kg of Hg"))(1" mol of Hg")/(200.59cancel(" g of Hg"))(59.11" kJ of heat")/(1" mole of Hg")

Cancel the units:

(0.06cancel(" kg of Hg"))/1(1000cancel(" g of Hg"))/(1cancel(" kg of Hg"))(1cancel" mol of Hg")/(200.59cancel(" g of Hg"))(59.11" kJ of heat")/(1cancel" mole of Hg")

Convert kJ of heat to J of heat:

(0.06cancel(" kg of Hg"))/1(1000cancel(" g of Hg"))/(1cancel(" kg of Hg"))(1cancel" mol of Hg")/(200.59cancel(" g of Hg"))(59.11" kJ of heat")/(1cancel" mole of Hg")(1000" J of heat")/(1" kJ of heat")

Cancel the units:

(0.06cancel(" kg of Hg"))/1(1000cancel(" g of Hg"))/(1cancel(" kg of Hg"))(1cancel" mol of Hg")/(200.59cancel(" g of Hg"))(59.11cancel" kJ of heat")/(1cancel" mole of Hg")(1000" J of heat")/(1cancel" kJ of heat")

Remove all of the canceled units:

(0.06/1)(1000/1)(1/200.59)(59.11/1) ((1000" J of heat")/1)

Perform the calculations (with 2 significant figures):

(0.06/1)(1000/1)(1/200.59)(59.11/1) ((1000" J of heat")/1) = 17700" J of heat"

This is an answer very close to selection A.