Asample of gold (au) has a mass of 72.04 g.

a) calculate the number of moles of gold (au) in the sample. show your work and highlight your final answer.

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b) a sample of gold (au) has a mass of 72.04g. calculate the number of atoms of gold (au) in the sample. (use your answer from part a.) show your work and highlight your final answer.

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question 2 a sample of sodium chloride (nacl) has a mass of 16.55 g.
a) calculate the number of moles of nacl in the sample. show your work and highlight your final answer.

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b) a sample of nacl (sodium chloride) has a mass of 16.55g. calculate the number of moles of na (sodium). calculate the number of moles of cl (chlorine). (hint; you can use your answer from part a as your starting point.) show your work and highlight your final answer.

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c) a sample of nacl (sodium chloride) has a mass of 16.55g. calculate the number of atoms of na (sodium). calculate the number of atoms of cl (chlorine). (hint; you can use your answer from part b as your starting point.) show your work and highlight your final answer.
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question 3 a sample of table sugar (sucrose, c12h22o11) has a mass of 5.432 g.

a) calculate the number of moles of c12h22o11 in the sample. show your work and highlight your final answer.

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b) a sample of table sugar (sucrose, c12h22o11) has a mass of 5.432 g. calculate the number of moles carbon. calculate the number of moles hydrogen. calculate the number of moles oxygen. (hint: you can use your answer from part a as your starting point.) show your work and highlight your final answer.

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c) a sample of table sugar (sucrose, c12h22o11) has a mass of 5.432 g. calculate the number of atoms carbon. calculate the number of atoms hydrogen. calculate the number of atoms oxygen. (hint: you can use your answer from part b as your starting point.) show your work and highlight your final answer.

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Question 1 : A) 0.365 mole , B) 2.2 * 10^23  atoms

Question 2: A) 0.283 mole , B) 0.283 mole , C) 1.7 * 10^23  atoms

Question 3: A) 0.016 mole ; B) C: 0.192 mole, H: 0.352 mole, O: 0.176 mole; C) C: 1.16 * 10^23  atoms, H: 2.12 * 10^23 atoms, O: 1.06 * 10^23 atoms

Explanation:

Question 1

A) Number of moles are calculated with the following formula:

number of moles = Mass / Molecular weight

mass of gold = 72.04 g

Molecular weight of gold = 197 g/mole

number of moles of gold = 72.04 / 197 = 0.365 mole

B) To calculate the number of atoms, the Avogadro number is needed, as follows :

Number of atoms = moles * Avogadro number

Avogadro number = 6.023 * 10^23 atoms/mole

Number of atoms of gold = 0.365 * 6.023 * 10^23 = 2.2 * 10^23  atoms

Question 2

A) Following the same procedure as before

mass of NaCl = 16.55 g

Molecular weight of NaCl = 35.5 + 23 = 58.5 g/mole

number of moles of NaCl  = 16.55 / 58.5 = 0.283 mole

B) Each molecule of NaCl has 1 atom of Na and 1 atom of Cl, that means each mole of NaCl has 1 mole of Na and 1 mole of Cl, so:

number of moles of Na = 0.283 mole

number of moles of Cl = 0.283 mole

C) Following the same procedure as before

Number of atoms of sodium = Number of atoms of chlorine =  0.283 * 6.023 * 10^23 = 1.7 * 10^23  atoms

Question 3

A) Following the same procedure as before

mass of sucrose = 5.432 g

Molecular weight of sucrose = 342.3 g/mole

number of moles of sucrose = 5.432 / 342.3 = 0.016 mole

B) Each molecule of C12H22O11 has 12 atoms of C, 22 atoms of H and 11 atoms of O, that means each mole of C12H22O11 has 12 moles of C, 22 moles of H and 11 moles of O, so:

moles of C = 12*0.016 = 0.192 mole

moles of H = 22*0.016 = 0.352 mole

moles of O = 11*0.016 = 0.176 mole

C) Following the same procedure as before

Number of atoms of C = 0.192 * 6.023 * 10^23 = 1.16 * 10^23  atoms

Number of atoms of H = 0.352 * 6.023 * 10^23 = 2.12 * 10^23  atoms

Number of atoms of O = 0.176 * 6.023 * 10^23 = 1.06 * 10^23  atoms

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explanation:

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