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In order to determine the content of sodium carbonate in edible flour soda, Li Tong designed and carried out the following experiments: 1. Weigh 3.4g flour soda sample in a beaker, add 20ml water and stir until the sample is completely dissolved; 2. Add enough CaCl2 solution to it until no precipitation is formed; 3. Filter and remove the precipitate After drying, the weight is 3.0g (regardless of the mass loss in operation). Please calculate: what is the mass fraction of Na2CO3 in edible flour alkali? (accurate to 0.1%)
Let the mass fraction of sodium carbonate in edible noodle soda be x.na2co3 + CaCl2 = CaCO3 ↓ + 2nacl106 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 1003.4g × X & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 3.0g106100 = 3.4g × x3.0g, X ≈ 93.5%. A: the mass fraction of sodium carbonate in edible noodle soda is 93.5%
A chemistry calculation problem in grade three of junior high school ~ online! Thank you
In order to determine the mass of NaOH solution, after dropping two drops of phenolphthalein test solution into 10g solution, neutralize it with dilute hydrochloric acid. When the red color just disappears, use 14.2ml of dilute hydrochloric acid with 10% density of 1.03g/cm3
Find 1. The mass of solute in NaOH solution
2. Mass fraction of solute in the obtained solution
The accuracy of the results was 0.1%
The mass of solute in hydrochloric acid is 1.03g/ml * 14.2ml * 10% = 1.46G
HCl+NaOH=NaCl+H2O
36.5 40 58.5
1.46g x y
36.5/1.46g=40/x=58.5/y
x=1.6g y=2.34g
1. The mass of solute in NaOH solution is 1.6g
2. The mass fraction of solute in the solution is 2.34g / (10g + 1.03g/ml * 14.2ml) * 100% = 9.5%
What is the letter of gas, solid and liquid in the chemical reaction equation
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