Prepare a solution Prepare 250 mL of a 0.22 M Na2CO3 solution. Steps 1. Calculate the mass of solute that you need. M n L n M L = = ⋅ → solute soluti n solute soluti n o o Substitute the data: nsolute = 0.22 M × 0.25 L = 0.055 mol Calculate its equivalent value in g: M(Na2CO3) = 23 × 2 + 12 + 3 · 16 = 106 g/mol 0.125 111 g 1 13.9 g of mol mol ⋅ = Na2CO3 2. Measure the mass of solute. 3. Dissolve it in a small amount of water. 4. Pour it into the graduated flask 5. Pour in water up to the full mark. Meniscus 6. Bottle and label it. 37 If you use 50 mL of 0.22 M Na2CO3 solution, what mass of solute do you use? 38 What volume of 0.22 M Na2CO3 solution do you need to obtain 1 g of Na2CO3? Conclusions 250 mL graduated flask Scales Watch glass, spatula and glass rod Beaker Na2CO3 Distilled water Materials 8. Solutions Correct eye position for measuring Full mark Na2CO3 0.22 M (date of production) 28
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