Assignment: 1. How many ml of 0.25 M NaOH will react with...

Assignment: 1. How many ml of 0.25 M NaOH will react with 10.0 ml of 0.10 M H2SO4. 2. 0.4671 g sample containing NaHCO3 (FW = 84.01 mg/mmol) was dissolved and titrated with 0.1067 M HCl requiring 40.72 mL. Find the percentage of sodium bicarbonate in the sample. 3. A 0.1876 g of pure sodium carbonate (FW = 106 mg/mmol) was titrated with approximately 0.1 M HCl requiring 35.86 ml. Find the molarity of HCl.

Transcript

00:01 First, we need to know what the balanced chemical reaction is between sodium hydroxide and sulfuric acid.

00:09 The products will be sodium sulfate and water.

00:15 To balance it, we need a 2 in front of the sodium hydroxide to get our two sodiums.

00:20 That will then produce two waters.

00:22 So to determine the milliliters of sodium hydroxide required to react with 10 .0 milliliters of the sulfuric acid, we convert the milliliters sulfuric acid into liters by dividing by a thousand.

00:39 We then convert the liters into moles using molarity.

00:44 One liter is 0 .10 moles at 0 .1 molar.

00:50 Molar.

00:51 This is moles sulfuric acid.

00:53 We'll then convert to moles sodium hydroxide, seeing it's a 1 to 2 mole relationship.

00:59 1 mole h2so4 requires 2 moles naoh.

01:05 Now that we have moles naoh, we can convert to liters naoh.

01:10 Using its molarity, 1 liter contains 0 .25 moles sodium hydroxide, but it wants milliliters, so one liter is 1000 milliliters, and we get 8 .0 milliliters of sodium hydroxide.

01:37 For the second question, it wants us to find the percent sodium bicarbonate in the sample, so we need to know what that reaction is.

01:47 Two moles hcl react with, actually it's just is 1 mole hcl, reacts with 1 mole sodium bicarbonate to produce 1 mole sodium chloride, 1 mole carbonic acid, which dissociates into carbon dioxide and water.

02:13 But what's most important is the stoichiometry here is 1 to 1.

02:19 So to find the percent sodium carbonate in the sample, we first need to find the mass sodium bicarbonate.

02:27 The mass can be calculated taking the 40 .72 milliliters of the hcl required to react with it.

02:37 We convert that into liters by dividing by a thousand and then convert the liters into moles using the molarity hcl.

02:48 One one liter is 0 .1067 moles hcl.

02:55 Then knowing the moles hcl, one mole hcl, we can calculate the moles sodium bicarbonate reacts with one mole sodium bicarbonate.

03:06 And then last of all, we convert the moles sodium bicarbonate into grams using the molar mass of sodium bicarbonate, which will be the mass of 1 mole sodium, 1 mole hydrogen, 1 mole carbon, and 3 moles of oxygen, 84 .007 grams...

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