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2 answers:
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Answer:
The mass of 1.26 mole of water, H₂O, is 22.68 grams
Explanation:
Molar mass is the amount of mass that a substance contains in one mole. In other words, the molar mass of an atom or a molecule is the mass of one mole of that particle and its unit is g/mole.
In this case, being:
- H: 1 g/mole
- O: 16 g/mole
the molar mass of water H₂O is:
H₂O= 2*1 g/mole + 16 g/mole= 18 g/mole
Then you can apply the following rule of three: if 18 grams are present in 1 mole of H2O, how much mass is present in 1.26 moles of water?
mass= 22.68 grams
<u><em>The mass of 1.26 mole of water, H₂O, is 22.68 grams</em></u>
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