2. A) If a 1.0-gallon (3.785L) bottle were filled with bleach (NaOCl), how many
ID: 1012198 • Letter: 2
Question
2. A) If a 1.0-gallon (3.785L) bottle were filled with bleach (NaOCl), how many Cl atoms would be in the bottle? Bleach=1.090 g/ml.
B) At 25°C, the density of water is 0.0997 gm/ml. At -10°c, the density of ice is 0.917 gm/cm3. If a bottle with a volume of 275 ml, were filled fully with water at 25°c, then frozen to -10°c, could the ice still be contained in the bottle? What would be the volume of ice be?
C) A sample of dry gas weighing 3.1134 gm is forced to occupy 7.2 L at 22°c and 740 mm Hg pressure. How many moles of the gas present?
Explanation / Answer
A)
we know that
mass = density x volume
so
mass of NaOCl = 1.09 x 3785
mass of NaOCl = 4125.65 g
now
moles = mass / molar mass
also
molar mass of NaOCl = 74.44 g /mol
so
moles of NaOCl = 4125.65 / 74.44
moles of NaOCl =55.4225
now
we know that
number of molecules = moles x 6.022 x 10^23
so
number of NaOCl molecules = 55.4225 x 6.022 x 10^23
number of NaOCl molecules = 3.3375 x 10^25
now
we can see that
1 molecule of NaOCl contains 1 Cl atom
so
number of Cl atoms = number of NaOCl molecules = 3.3375 x 10^25
B)
we know that
mass = density x volume
so
mass of water in the bottle = 0.997 x 275
mass of water in the bottle = 274.175 g
now
when water is converted to ice , mass remains constant
so
mass of ice = 274.175 g
now
volume = mass / density
so
volume required for ice = 274.175 / 0.917
volume required for ice = 299 ml
but volume of the bottle is 275 ml
so
the ice cannot be contained in the bottle
the volume of ice will be 299 ml
C)
we know that
for gases
PV = nRT
given
pressure = 740 mm Hg = 740 / 760 atm
volume (V) = 7.2 L
temperature (T) = 22 + 273 K = 295 K
so
using those values
we get
(740/760) x 7.2 = n x 0.0821 x 295
n = 0.29
so
0.29 moles of the gas is present
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