corrected question:
Determining Density and Using Density to Determine Volume or Mass
(a) Calculate the density of mercury if 1.00 × 10 g occupies a volume of 7.36 cm³
(b) Calculate the volume of 65.0 g of liquid methanol (wood alcohol) if its density is 0.791 g/mL.
(c) What is the mass in grams of a cube of gold (density = 19.32 g/cm) if the length of the cube is 2.00 cm?
(d) Calculate the density of a 374.5-g sample of copper if it has a volume of 41.8 cm³ A student needs 15.0 g of ethanol for an experiment. If the density of ethanol is 0.789 g/mL, how many milliliters of ethanol are needed? What is the mass, in grams, of 25.0 mL of mercury (density = 13.6 g/mL)?
Answer:
density = 
ρ=m/v ,m=ρv, v=m/ρ
(a)m=1*10g , v=7.36cm³
ρ=10/7.36 =1.36g/cm³
(b) m=65g, ρ=0.791 g/mL.
v= 65/0.791 =82.17g/mL
(c) ρ=19.32g/cm³, l=2cm, v=l³=8cm³
m=19..32*8=154.56g/cm³
(d) mass of copper=374.5g , v=41.8cm³
ρ=374.5/41.8 =8.96g/cm³
mass of ethanol=15g, density of ethanol=0.789g/mL
v=15/0.789 =19.01mL
volume of mecury=25mL, density of mercury=13.6g/mL
m=25*13.6=340g
The molar mass of carbon (C) is 12.0107 u.
Answer: the reaction will produce 15.3 g of
KCl.
explanation:
1. write the balanced equation.
2KClO
3
→
2KCl
+
3O
2
2. calculate the moles of
KClO
3
.
Moles of KClO
3
=
25.0
g KClO
3
×
1 mol KClO
3
122.55
g KClO
3
=
0.2046 mol KClO
3
3. calculate the moles of
KCl
.
Moles of KCl
=
0.2046
mol KClO
3
×
2 mol KCl
2
mol KClO
3
=
0.2046 mol KCl
4. calculate the mass of
KCl
.
Mass of KCl
=
0.2046
mol KCl
×
74.55 g KCl
1
mol KCl
=
15.3 g KCl