A 0.500-g sample containing Na2CO3 plus inert matter is analyzed by adding 50.0 mL of 0.100 M HCl, a slight excess, boiling to remove CO2, and then back-titrating the excess acid with 0.100 M NaOH. If 5.6 mL NaOH is required for the back-titration, what is the percent Na2CO3 in the sample?

Answers

Answer 1

The percentage by mass of Na2CO3 in the sample is 48%.

The equation of the reaction of Na2CO3 with HCl;

Na2CO3(aq) + 2HCl(aq) ------> 2NaCl(aq) + H2O(l) + CO2(g)

Since the HCl is in excess, the excess is back titrated with NaOH as follows;

NaOH (aq) + HCl(aq) ---->NaCl(aq) + H2O(l)

Number of moles of HCl added =  0.100 M × 50/1000 L = 0.005 moles

Number of moles of NaOH added = 5.6/1000 ×  0.100 M = 0.00056 moles

Since the reaction of NaOH and NaOH is 1:1, 0.00056 moles of HCl reacted with excess HCl.

Amount of HCl that reacted with Na2CO3 =  0.005 moles -  0.00056 moles = 0.0044 moles

Now;

1 mole of Na2CO3 reacts with 2 moles of HCl

x moles of Na2CO3 reacts with 0.0044 moles of HCl

x = 1 mole × 0.0044 moles / 2 moles

x = 0.0022 moles

Mass of Na2CO3 reacted = 0.0022 moles × 106 g/mol = 0.24 g

Percentage of Na2CO3  in the sample = 0.24 g/ 0.500-g × 100/1 = 48%

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The first image shown at the left hand side is a pi bond. The other two images show sigma bonds.

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1. List the ketose carbon(s) that is(are) reduced with NaBH4.

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Answer:

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Why does the Hubble Space Telescope take clearer pictures than other telescopes?

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Space-based telescopes like Hubble get a much clearer view of the universe than most of their ground-based counterparts. ... Ground-based telescopes can't do the same, because the Earth's atmosphere absorbs a lot of the infrared and ultraviolet light that passes through it.

what are the solar home lighting​

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Answer:

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Answer: During aerobic respiration, catabolic reactions convert larger complex organic molecules into ATP, the chemical that drives most physiological processes in the body.

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calculate the mass percentage of each element in aluminum oxide.Then calculate themass of aluminum in a 3.62 gram sample of of aluminum

Answers

1. The mass percentage of each element in aluminum oxide Al₂O are:

i. The mass percent of Al in Al₂O₃ is 52.9%

ii. The mass percent of O in Al₂O₃ is 47.1%

2. The mass of Al in 3.62 g of Al₂O₃ is 1.73 g

1i. Determination of the percentage of Al

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Percentage of Al = (54 / 102) × 100

Percentage of Al = 52.9%

1ii. Determination of the percentage of O

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Percentage of O = 47.1%

2. Determination of the mass of Al in 3.62 g of Al₂O₃.

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Which of the following best represents a ​chemical change?

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Answer:

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Answer:

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I’m a genius and it’s the answer :D

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Answer:

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Answer:
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Answers

Answer:

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Answer:

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Answer:

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Answers

First of all, you need to convert mL to L; 120mL = 0.12L, 300mL = 0.3L.

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Answers

Answer:

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Answer:

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Explanation:

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