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Topic: Chemistry
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Purpose: We will determine how much hydroxide is available in 20, 0 cm3 saturated calcium solution, calculate the amount of dissolved calcium and calculate the saturated calcium hydroxide concentration. We will learn to count with concentration, amount of substance and volume.

Introduction: We should titrate, pour a few drop of hydrochloric acid from the pipette into a calcium hydroxide solution and get a neutral solution that is to put equal amount of substance of a substance to another topic so that they have an equal amount of substance. Then you get a neutral solution that you have reached the equivalence point.

Material: Burette, Vollpipett, flask, funnel, fine filter paper, cups, spoons, calcium hydroxide, hydrochloric acid
Construction: All materials were developed and the piston was filled with 50 cm3 = 50 ml with deionized water. A spoon calcium hydroxide was poured. This forms formula Ca (OH) 2. We put on a stopper and shook. The flask was shaken so that it gets really mixed but one could see that not everything could be resolved. The mixture turned cloudy and gray. Another flask was derived and et filter paper was folded and placed in. Mixture is poured through the filter up to 20 ml. There, stuck portion of calcium hydroxide powder on the filter (the one that had not been resolved with the water) and we concentrated saturated calcium hydroxide solution. Some BTB drops dripped into the solution, it allows us to see the change in color when the solution goes from basic to neutral to acidic. At basic solutions shows the blue, at neutral pH values ​​displaying the color green and the acidic shows the yellow. We put it under the burette with the hydrochloric acid. We noted carefully how much hydrochloric acid that was originally because through it you can figure out how much acid was needed to get a neutral solution. Hydrochloric acid was dropped in and the color of calciumhydroxidlösningen changed to green. We noting how much hydrochloric acid that was left in the burette. In this way, we took X ml of hydrochloric acid from the start minus so much that was left when the solution changed color to get the amount of hydrochloric acid that had been used to neutralize the solution. We made three attempts to compare the measurements.

Filtration: Titration

Saturated calcium hydroxide solution
Ca (OH) 2

OH + H + H2O
By knowing these forms so we know that the amount of hydrogen ions is the same as the amount of hydroxide ions in the solution because the solution became neutral. Since I know how much I poured into hydrochloric acid so I can figure out the amount of substance, and thus I know also the amount of substance of OH in the calcium hydroxide. I took the molar mass of hydrogen and Cl (looked in the periodic table) and added these to find out HCI's molar mass. I know also that the concentration of hydrochloric acid, which means that I can figure out the hydrochloric acid amount of substance (n). I do this by multiplying the concentration by volume (dm3). Then I know that the amount of substance of the H + and thus also for the OH because it was the same.
Although the amount of dissolved calcium hydroxide can I determine by looking at the formula:
Ca (OH) 2 Ca2 + (aq) + 2OH- (aq)
I divided the result by 2 to get loose calcium hydroxide. To then get the saturated concentration kalciumhydroxidlösningens I took the amount of substance for calcium and divided by the volume in cubic centimeters.


HCl from the start in Burette (ml) of HCl left (ml) Difference
(Ml) Ca (OH) 2 in the flask (mL) neutral solution (ml) Acidic
40 47.8 7.8 20 27.8
47.8, 14.1 * 50 16.5 * 4.7 20 24.7
17.8 23.8 6 20 26
* Hydrochloric acid ran out and we filled in and so we got different dimensions to count to find out the difference.

The difference = HCl from start-HCl left

HCl = 1,0079g / mole + 35.45 g / mole = 36,4579g HCl / mol
The volume of Ca (OH) 2 = 0.020 dm3
The concentration of hydrochloric acid = 0,100mol / dm3
Amount of substance HCl = 0.0006 mol
Subtansmängd OH = 0.0006 mol
Amount of substance Ca2 + = 0.0003 mol
Molar mass of Ca (OH) 2 = 74.058 g / mol
Mass dissolved kalciumhydroxidCa (OH) 2 = 0,0222g
Concentration of saturated calcium hydroxide solution = 0.15 mol / dm 3

Answer: There are 0.0006 moles of hydroxide ions 20,0cm3 calcium hydroxide. The amount of dissolved calcium hydroxide is 0.0222 g. Kalciumhydroxidlösningens The saturated concentration is 0.15 mol / dm 3

Conclusion: The implementation of our experiments, we got different results. In experiment 1, we received an acidic solution because we happened to take too much hydrochloric acid in the solution, so we got an acidic solution, it became yellow. By looking at the results for the other two trials, I could see that it took about 5 ml of hydrochloric acid to neutralize the alkaline calcium hydroxide.

How many hydroxide ions are there in 20.0 cm3 of saturated calcium hydroxide solution? Calcium hydroxide is a basic substance and is therefore composed of hydroxide ions. Calcium hydroxide is a fairly sparingly soluble substance but can form lime water that is saturated calcium hydroxide in this lab. When to neutralize the calcium hydroxide, it means we have to have the same amount of hydrogen ions (H +) as hydroxide ions as there are hydrogen ions in an acidic solution and hydroxide ions in monobasic. If we mix the same amount of the solution becomes neutral. Once we know how much hydrochloric acid we dropped in to get a neutral solution, we can find out how many there were in hydroxide solution from the beginning. I assume three attempts we did. We poured in 6 ml of hydrochloric acid = 0.006 dm3 We need to figure out how many kubikdecimetrar it is because measuring the concentration (molar) in cubic centimeters. We are looking for substance quantity of hydrochloric acid and therefore must take the volume of hydrochloric acid multiplied by the concentration is greater. This formula shows us that in a neutral solution is always as many hydroxide ions as hydrogen ions. H ++ OH = H2O. With subtsansmängden of hydrochloric acid, we have the answer for hydroxidjonernas amount of substance.

When we have to determine calcium ions mass, we must first determine their amount of substance.
Ca (OH) 2 Ca2 + (aq) + 2OH- (aq)
1mol 1mol + 2mol
Then I see that there are two hydroxide ions in a calcium ion divides I hydroxidjonernas amount of substance in the second with two unknown numbers in a formula can not be solved so I must find the molar mass of calcium hydroxide by looking at the periodic table and add these to get formula mass of calcium hydroxide. The pulp is then = molar mass x amount of substance

As I know the amount of substance for calcium in previous calculations by dividing I with the volume to get the concentration of the saturated calcium hydroxide solution.

In carrying out this assignment, I have come to the conclusion that very little more hydrogen ions than hydroxide ions to make the solution neutral, it is about getting exactly the same number to get a neutral solution. A trembling hand be crucial if one fails in the attempt to get a neutral solution which happened to us in the first attempt. In order to calculate the net asset amount of calcium hydroxide, hydroxide ions, the concentration of calcium hydroxide, etc., one must know the relationship between volume, concentration, and amount of substance. Although the relationship between molar mass, amount of substance and mass is crucial to be able to carry out these tasks we got to.

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