You have 40g of MgCl2. How many atoms of Cl are in the sample? Chemistry The Mole Concept The Mole 1 Answer Junaid Mirza Mar 4, 2018 #5.07 × 10^23# Explanation: Molar mass of #"MgCl"_2 = "95 g/mol"# Moles of #"MgCl"_2# in given sample #= "40 g"/"95 g/mol" = "0.421 mol"# Moles of #"Cl"# atoms in given sample #= 2 × "0.421 mol" = "0.842 mol"# Number of #"Cl"# atoms #= 0.842 cancel"mol" × (6.022 × 10^23)/cancel"mol" = 5.07 × 10^23# Answer link Related questions How do you calculate the number of moles from volume? How do you convert grams to mole? Question #258e5 Question #8d48c Why is the mole an important unit to chemists? What's the mole number? How does the mole relate to carbon 12? How does the mole relate to molecules and ions? How do you calculate the moles of a substance? How can I calculate the moles of a solute? See all questions in The Mole Impact of this question 17576 views around the world You can reuse this answer Creative Commons License