Lab Report 7 Investigating stoichiometry with Sodium Salts of Carbonic Acid

Stoichiometry is a very important part of chemistry. Stoichiometry refers to calculating the masses of molecules and their products . The reactants are usually given and stoichiometry is used to find the products of the equations as well balancing the equation. An example of this would be sodium chloride (NaCl). Stoichiometry will say that if there are ten thousand atoms of sodium and one atom of chlorine, only one molecule of sodium chloride can be made and that fact can never be changed.

First, we were to measure and record the mass of a beaker, then transfer about 1 gram of the salt mixture into the beaker, measure, and record the combined mass. Then, we had to fill a 400-ml beaker with deionized water and test it to make sure that the ph was just basic. We then combined the deionized water and salt by adding about 150ml of the deionized

As a group, we obtained our salt mixture of calcium chloride and potassium oxalate, and weighed the mixture. We were able to make an aqueous solution from the mixture and distilled water. We boiled and filtered off the solution, leaving the precipitate. Once the precipitate was dried overnight, it was weighed and the mass was measured. Then we calculated the moles of the precipitate.

The procedures for experiment A, B, and C all start the same. The first step is to put on goggles and get the data collection device set properly. The labquest needs to be plugged into the colorimeter accurately so that a click is heard when putting it in. The labquest needs to be reading digitally and the colorimeter needs to be set to 635 nm. Then shake the chloroplast solution and take a clean cuvette and fill it with 3 mL of distilled water, 3 drops of the chloroplast solution, and cap it. This is used as a blank to calibrate your labquest. Double check that the labquest is reading absorbance, this assures that the colorimeter is plugged into the labquest accurately. Insert the blank into the colorimeter and hit the calibration button. Take out the blank and empty it. The labquest is now set to experiment with. Make sure that the heat bank is set in front of the lamp and that the lamp is on. The cuvette must be placed on the opposite side of the heat bank in the path of light in the box so that no other light can interfere with the experiment.

Enter the precise mass in GRAMS of the potassium iodate used to prepare your primary standard solution.

Discard the solution in the appropriate container as directed to you by your lab instructor.

Measure 500ml of tap water in the 500cm3 beaker, then measure 5g of sodium hydrogen carbonate using the 50cm3 beaker and weight scale and place in the beaker of water, using the glass rod to dissolve it into the mixture.

Then we took 8.35mL of salt water and put it in the evaporating dish which we placed over a Bunsen burner until all the water was dried out. The mass of the evaporating dish with the solid was 83.39g which means the mass of the sodium chloride was 0.622g. Next we took the mass and divided it by the volume of the solution which was 8.35mL and got 0.074 as the original concentration. To the get molarity of the salt solution we had to divide the concentration by the mass of the sodium chloride and then multiply by 1000mL to get 1.3M of salt solution. Final thing we had to do was determine the number ions present in 8.35mL so we took 1.3 moles of NaCl and divided it by 1000mL then multiplied by 8.5mL to get 0.01105 number of Na ions and Cl. The data was as I expected for part A because I followed step by step instructions on how to convert from grams to moles and moles to number of molecules and for part B my answer of 1.3 molarity of salt solution matched with key provided on LoudCloud.

7. Using the slider on the right hand side, add NaOH to the HCl in the Erlenmeyer flask (This action is known as titrate). Add the indicator until the color of the indicator turns a light shade of pink.

3. A student wanted 20.000 g of a salt. Which balance should the student use in order to

Weigh the beaker with water in it, record this value in Data Table 1 and subtract the mass of the beaker to get the mass of the water. Record this value in Data Table 1.

14) Let the crystals of the silver settle in the plastic container and decant off the liquid.

If you see a deep blue color add more zinc powder until there is no change in color of the solution in the test tube.

Before the lab began, stoichiometry was used to predict the net weight of the solids for each reaction. For each trial, the crucible was weighed to calculate the true weight of the NaHCO3 sample before and after it decomposes. A 2g sample of NaHCO3 was weighed out in the crucible. Using a Bunsen burner, the sample of NaHCO3 was heated past 200°C for 4 minutes to allow a thermal decomposition reaction to occur. The sample was taken out of the heat and its weight was recorded to measure the weight of the new solid. The sample was put back into the heat for an additional 4 minutes and weighed again until there was no significant change in the weight to ensure that the reaction had taken place. After washing out the crucible to remove the possibility of a different reaction with the solid and to obtain

= (89.14 + 83.72 + 82.7 + 86.54 + 93.87 + 88.88 + 92.5 + 90 + 97.5) ÷ 9