A sample of approximately 5 grams of sodium hydroxide (MM 40) was weighed on an electronic balance. Its mass was found to be 5.224 grams. This sodium hydroxide was dissolved in sufficient water to make 700 mL of solution. What is the molarity of the solution? Enter your answer with three significant figures.
2007-06-18 08:48:47 · 5 answers · asked by Division12 2 in Science & Mathematics ➔ Chemistry
Molecular weight of NaOH = 39.997 g/mol
moles NaOH = 5.224 g / 39.997 = 0.131
V = 700 mL = 0.700 L
M = moles / V = 0.131 / 0.700 = 0.186 M
2007-06-18 08:53:10 · answer #1 · answered by Dr.A 7 · 0⤊ 0⤋
The forumla for molarity is "M" (Molarity) = "m" (moles of solute, the substance being dissolved over "v" (volume of solvent in litres)
In your case, you have 5.224 grams of sodium hydroxide (NaOH).
Your first step would be to calculate the number of moles. First, the number of grams in one mole of substance is found. Normally, adding up the individual atomic weights of sodium, oxygen, and hydrogen (the three atoms present in this forumla) would reveal this, but it is already given to you as 40.
Second, divide the amount of substance present (5.224) by the molar mass (40). This gives you an amount of 0.1306. However, since you are using 3 sig fig's (significant figures), round the number to 0.131.
This number is then divided by the volume of solvent (water in this case) in litres. Based on the metric system, 700 mL of water is equal to 0.7 litres of water.
0.131 (moles of substance) divided by .7 (litres of water) produces a solution with a molarity of 0.187.
This number tells someone that there are 0.187 moles of sodium hydroxide (NaOH) in every 1.0 litre of water.
2007-06-18 09:09:26 · answer #2 · answered by prometheus2508 1 · 0⤊ 0⤋
a million) molar mass of KCl= seventy 4.5g, so moles = eighty 5/seventy 4.5. Molarity = moles consistent with liter, so take the moles (eighty 5/seventy 4.5) and divide it via the liters (.4). 2) 2/.15 = x13 a million/3. So 250mL / 13 a million/3 = 18.75 mL. or you will possibly be able to desire to u MV= MV. (2)(x)= (.15)(250)
2016-12-08 12:46:51 · answer #3 · answered by ? 4 · 0⤊ 0⤋
moles=mass(gr)/Molecular Mass(g/mol)
Molarity= moles/Volume (liters)
As easy as introducing your numbers on the formulas
2007-06-18 08:57:14 · answer #4 · answered by Manuelon 4 · 0⤊ 0⤋
Llamas Cheese And PIE!
2007-06-18 08:51:36 · answer #5 · answered by Crazy4Reeses 2 · 0⤊ 3⤋