A 4.5% NaCl solution has a density of 1.10g/mL. What is the molarity of the solution?
The answer is .847M, I just dont know how to get that answer!
2006-12-14 17:42:40 · 3 answers · asked by Jay 2 in Science & Mathematics ➔ Chemistry
You are given the amount of matter in 1 mL of space. 4.5% of that matter is NaCl. That means there exists 0.0495g of NaCl per mL of space (4.5g NaCl/100g solution * 1.10g solution/mL). Next find the amount of moles of NaCl (0.0495g/mL * 1 mol NaCl/58.44g NaCl) which is 8.47e-4 mol NaCl/mL. Since Molarity = mol/liter, convert mL into L and you have your answer (8.47e-4 mol NaCl/mL *1000mL/L = 0.847M)
2006-12-14 17:58:17 · answer #1 · answered by Dan O 2 · 0⤊ 0⤋
% solutions normally mean grams of solute (the NaCl) per 100 grams (=100mL) of water; but molarity is always expressed as amount of solute per Liter.
Density of water = 1.00g/mL
Because solution has density of 1.10g/mL (=110% water),
4.5% = 4.95g/100mL
BUT, since molarity is expressed per Liter, 4.95g/100mL = 49.5g/L
NaCl molar mass = 58.442
So, 49.5/58.442 = 0.847M
2006-12-14 18:06:55 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Weight of Nacl in 1L
4.5% = 45 *1.1 g/l = 49.5 g/l
as the molecular weight of Na Cl is 35.5 +23 =58.5g/l
the molarity is
49.5/58.5 =0.846M
2006-12-14 17:53:56 · answer #3 · answered by maussy 7 · 0⤊ 0⤋