Math conversion factor question help? 10 pts! ?

Question

when i carry a 5 gallon container of water from my car, i always wonder its weight. i looked up on the web and found that 1 lb = .0453542 kb and 1 qt = .946353 liter. calculate its weight in pounds.

and

what is the mass of a 1.00 gallon of mercury? [1 cup = 236.588 mL] [density of liquid mercury is 13.6 g/mL] [density = volume / mass]

and show me the work pleasee!

Answer 1

The first answer is 8 1/3 lbs per gallon ->> 5 * 8 1/3 = approx. 41 2/3 lbs.

Answer 2

You first need to know the density of the water.  This changes depending on temperature, but not much.  If you assume that it is 1 g/cm^3, it will make the math easier, and it really isn't a bad assumption.  If you have 5 gallons of water, you have 20 quarts. 4 quarts to a gallon.  20 quarts equals 18.93 liters.  18.93 liters equals 18,930 mL.  1mL=1cm^3.  So with a density of 1, you have 18930 grams of water, or 18.93kg, or 41.74 lbs.   NOTE: your conversion factor for pounds to kg is wrong.   A good rule of thumb is that a gallon of water weighs 8 lbs.

I'm not going to solve the mercury one, but I'll help you get it started.

Convert 1 gallon to cups, convert cups to mL.  Multiply volume by density to find mass.  NOTE: density=mass/volume.