Chemistry Help?

2019-03-09 1:26 am
1. How many grams of CaCl2 should be dissolved in 615.4 mL of water to make a 0.19 M solution of CaCl2?


2.What mass of NaOH is in 190 mL of a 4.3 M NaOH solution?

回答 (1)

2019-03-09 1:37 am
✔ 最佳答案
1.
Molar mass of CaCl₂ = (40.1 + 35.5×2) g/mol = 111.1 g/mol

Moles of CaCl₂ = (0.19 mol/L) × (615.4/1000 L) = 0.1169 mol
Mass of CaCl₂ = (0.1169 mol) × (111.1 g/mol) = 13 g

OR:
(0.19 mol/L) × (615.4/1000 L) × (111.1 g CaCl₂ / mol)
= 13 g

====
2.
Molar mass of NaOH = (23.0 + 16.0 + 1.0) g/mol = 40.0 g/mol

Moles of NaOH = (4.3 mol/L) × (190/1000 L) = 0.817 mol
Mass of NaOH = (0.817 mol) × (40.0 g/mol) = 32.7 g

OR:
(4.3 g/mol) × (190/1000 L) × (40.0 g NaOH/mol)
= 32.7 g NaOH


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