Answer:
5) How many moles does 80 grams of H2) represent?
The molar mass of water can be calculated by adding molar mass of the individual elements:
1 g/mol + 1 g/mol + 16g/mol = 18 g/mol of H2O
We need to calculate moles in 80 gram of water, therefore,
80 g H2O × 1mol H2O/18g H2O
= 4.44 mol H2O
6) What is the mass of 2.0 moles of LiOH?
The mass can be calculated by multiplying number of moles by its molar mass. In this case,
n = 2.0, and
molar mass = 23.95g/mo
We know that
mass = n × molar mass.
= 2.0mol × 23.95g/mo
= 48g
7). How many atoms does 2.0 moles of He represent?
The number of atoms can be calculated by using the formula
n (mol) = number of atoms / avogadro's number ([tex]N_{A}[/tex])
We can write it as follows,
number of atoms of He = n (mol) · [tex]N_{A}[/tex]
We know that [tex]N_{A}[/tex] is equal to 6.02X10^23. Hence, the total number of atoms can be calculated as follows,
number of atoms of He = 2.0 moles X (6.02X10^23)
= 12.04X10^23 atoms
8). Convert 3.01x10^23 molecules of C2H6 to moles.
Number of molecules (N) can be converted to the number of moles (n) using the following formula
[tex]n = \frac{N}{N_{A}}[/tex]
By putting values,
= 3.01x10^23 / 6.02X10^23
= 0.5 moles
9). What would be the mass of 1.20 x 10^24 molecules of water?
To calculate the mass, we will first need to calculate the number of moles of water using following formula,
number of moles = number of molecules / avogadro's number.
number of moles = 1.20x10^24 / 6.02x10^23
number of moles = 1.99.
Then, we will multiply number of moles of water by water's molecular mass.
mass = 1.99 x 18.0 g/mol
mass = 35.8 g water
10) How much mass does 1.51 x 10^22 atoms of neon represent?
The total mass can be calculated using the following approach,
mass = number of atoms x (1 mole / avogadro's number) x neon molecular mass
= 1.51x10^22 atoms x (1 mole / 6.022x10^23 atoms) x (20.18 g/mole)
= 0.503 g Ne
