Sodium Carbonate Lab Report

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Write the equation for the dissolution of sodium carbonate in water as found in your laboratory guide.
When sodium carbonate is dissolved in water, it doesn’t dissociate, or break up, completely. There is always some sodium carbonate in solution. Knowing this, which of the two samples is most alkaline? Explain why you say this.
Answer:

Na2CO3 + H2O ---> 2NaOH+ + H2CO3-2

Sodium carbonate is the resulting salt of a strong base and a weak acid. Thus, when it is dissolved in water, NaOH, strong base, and H2CO3, weak acid, are the products of the hydrolysis. The OH ions from the strong base are predominant in solution and deprotonate H2CO3 to form another conjugate base, HCO3 and CO3. As a result, the overall pH of the solution is alkaline due …show more content…

They use this exact kit, so what you have done is on-the-job training. There is a difference, however. These kits were set up using water samples provided for you. In real-life situations, workers collect water samples in a lake or stream instead of using Samples A and B that you tested. For this lab to work, sodium carbonate was added to make the water samples alkaline. In lakes and streams it is calcium carbonate (CaCO3) that causes alkalinity. Calcium carbonate acts as a buffer, a substance that serves to resist small changes in acidity or alkalinity in a solution. When acid rain enters lake water, it can be neutralized by the bases present and thus the lake does not become too acidic. Since the key ion is the hydroxide ion, the nature of the cation doesn’t matter in this case. All over the world, right now, pollution workers are measuring calcium carbonate in lakes and streams.
If a worker studied two lakes and Lake X had a greater ppm of calcium carbonate than Lake Z, which of the two lakes would be able to withstand a greater amount of acid rain? Explain your answer.
Answer:

Lake X would be able to withstand a greater amount of acid rain because it has a greater buffering capacity due to the higher concentration of calcium carbonate present that will react with the excess acid. As a result, it would be able to better resist changes

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