Question

Write the steps to solve the following:

a) Convert 2.75 g Na to moles Na.

b) Convert 4.7 moles H2O to grams H2O.

c) Convert 1.18 x 10^26 atoms Au to moles Au.

d) Convert 0.95 moles Cu to atoms Cu.

e) Convert 1.34 x 10^15 atoms of Zn to grams Zn.

f) Convert 0.82 g Ag to atoms Ag.

Answer 1

To convert grams of Na to moles of Na, divide the given mass by the molar mass of Na. To convert moles of H2O to grams of H2O, multiply the given number of moles by the molar mass of H2O. To convert atoms of Au to moles of Au, divide the given number of atoms by Avogadro's number. To convert moles of Cu to atoms of Cu, multiply the given number of moles by Avogadro's number. To convert atoms of Zn to grams of Zn, divide the given number of atoms by Avogadro's number, then multiply by the molar mass of Zn. To convert grams of Ag to atoms of Ag, divide the given mass by the molar mass of Ag, then multiply by Avogadro's number.

Step-by-step explanation:

1. Start by determining the molar mass of Na, which is approximately 22.99 g/mol. Then, divide the given mass of Na (2.75 g) by the molar mass to obtain the number of moles: 2.75 g / 22.99 g/mol = 0.119 mol Na.
2. To convert from moles to grams, you can use the molar mass of H2O, which is approximately 18.015 g/mol. Multiply the given number of moles of H2O (4.7 moles) by the molar mass to obtain the mass: 4.7 moles * 18.015 g/mol = 84.63 g H2O.
3. For this conversion, you will need Avogadro's number, which is approximately 6.022 x 10^23 atoms/mol. Divide the given number of atoms of Au (1.18 x 10^26 atoms) by Avogadro's number to obtain the number of moles: 1.18 x 10^26 atoms / 6.022 x 10^23 atoms/mol = 196 mol Au.
4. To convert from moles to atoms, you can use Avogadro's number. Multiply the given number of moles of Cu (0.95 moles) by Avogadro's number to obtain the number of atoms: 0.95 moles * 6.022 x 10^23 atoms/mol = 5.72 x 10^23 atoms Cu.
5. First, determine the molar mass of Zn, which is approximately 65.38 g/mol. Then, divide the given number of atoms of Zn (1.34 x 10^15 atoms) by Avogadro's number to obtain the number of moles: 1.34 x 10^15 atoms / 6.022 x 10^23 atoms/mol = 2.22 x 10^-9 mol Zn. Finally, multiply the number of moles by the molar mass to obtain the mass: 2.22 x 10^-9 mol * 65.38 g/mol = 1.45 x 10^-7 g Zn.
6. To convert from grams to atoms, you need the molar mass of Ag, which is approximately 107.87 g/mol. Divide the given mass of Ag (0.82 g) by the molar mass to obtain the number of moles: 0.82 g / 107.87 g/mol = 0.0076 mol Ag. Then, multiply the number of moles by Avogadro's number to obtain the number of atoms: 0.0076 mol * 6.022 x 10^23 atoms/mol = 4.58 x 10^21 atoms Ag.