Calculation of the mass fraction of the chemical solute in combination with the chemical equation

Process or answer?

caco3+ 2hcl = h2o + co2 + cacl2x y z

Chlorine is calculated according to 36, I don't know if you are calculated, the principle is the same) solution x=y= (calculate it yourself).

z = the mass fraction of the solute sought = z (x+ -y)=1), because when the first time is added, the solid is reduced by 5g, the second time is added, the solid is reduced by 5g again, and the third time is added, the solid is less, indicating that the remaining solid is an impurity that does not react with dilute hydrochloric acid.

3） caco3+ 2hcl = h2o + co2 + cacl2x

Only 60g of x=dilute hydrochloric acid was used to solve the solution, and the reaction did not continue.

So the mass fraction of solute in dilute hydrochloric acid = (x 60) * 100% =

If you don't have a question, you let me count anything, and if I don't understand the basic knowledge points, I will read the book by myself.

The following is the formula for calculating the quantity concentration of a substance in a solution, which expresses the relationship between the quantity concentration of a substance and the mass fraction and the density of the solution.

c=1000 m unit is g mol where.

1000--1000ml

The density of the solution is in g ml

Mass fraction of the solute in solution, in %

m - the mass of the solute.

cm/1000ρ

1) According to the law of conservation of mass: total mass before reaction = total mass after reaction, let the mass of CO2 be x, that is, 11g + 50g = x of the solution = let the mixture contain soda ash YGNA2CO3 + 2HCl = 2NaCl + CO2 rise + H2OYG

106 44 Solutiony=

2) The mass fraction of soda ash is:

Solution: Let the mass of carbon dioxide generated be x, and the solute mass fraction of dilute hydrochloric acid used is YCAC3+2HCl=CaCl2+H2O+CO2 (gas symbol) 100 73 44

25*80% 100y x

100/(25*80%)=73/100y=44/xx=

y = A: (1) The mass of carbon dioxide produced is grams.

2) The solute mass fraction of dilute hydrochloric acid used is:

Because 25g contains calcium carbonate, 80% of marble contains calcium carbonate mass = 25g * 80% = 20g

Assuming that the solute mass fraction of dilute hydrochloric acid used is x, the mass of carbon dioxide produced is YCAC3 + 2HCl = CAC2 + H2O + CO2 100 73 44

20g 100g*x y

100 44 = 20g 100g * x x = 100 44 = 20g y y = 1) The mass of carbon dioxide produced is grams;

2) The solute mass fraction of dilute hydrochloric acid used is:

Let the mass of carbon dioxide produced be x; The solute mass fraction of dilute hydrochloric acid used is YCAC3 + 2HCl = CaCl2 + H2O + CO2 100 73 44

25g×80% y x

100:44=25g 80%:x, solution x=100:73=25g 80%:100y, solution y= Answer: The mass of carbon dioxide generated is, and the solute mass fraction of hydrochloric acid used is.

Caco Relative Molecular Mass:;

CO2 relative molecular mass:

HCl relative molecular weight:

CaCo +2HCl = CO2 + GACl2 + H2O Each molecule of calcium carbonate can release 1 molecule of carbon dioxide.

The mass of carbon dioxide is 25*80% 100*44 = each calcium carbonate molecule reacts with 2 hydrochloric acid molecules.

The mass fraction of hydrochloric acid is 25*80% 100*

CaCO3 + 2HCl = CaCl2 + H2O + CO2 (gas symbol) 100 2 * 44

25*80% 100y x

100/(25*80%)=73/100y=44/xx=

y = A: (1) The mass of carbon dioxide produced is grams.

2) The solute mass fraction of dilute hydrochloric acid used is:

Since all the reactions, it proves that all the calcium carbonate is consumed, first find the mass of calcium carbonate that actually participates in the reaction, that is, 25g*80%, and then find the mass of carbon dioxide and the mass of hydrochloric acid that actually participates in the reaction according to the chemical equation, and then divide by 100g is the mass fraction of hydrochloric acid.

20gcaco3 generated.

The consumption quality score is:

1 The meaning of the sentence of the mass fraction of the solute itself is to be understood, the expression: the mass of the solute The mass of the solution is multiplied by 100%. The last dissolved is not counted as a solute and cannot be counted as a solution part.

An important factor that interferes with the thinking is the understanding of percentages, and the rest of the above problems is the calculation of chemical equations. In addition, the calculated data placed in the chemical equation must be the data of the pure substance, and the common mistake is to put the mass of the mixture in the chemical equation.

2 Calculation of chemical formulas: The reason why I can't do it is that I can't understand the meaning of the topic and the concept is confused.

Anything that involves "number" is counted directly by looking at the chemical formula. Wherever the word "mass" is involved, the relative atomic mass is used. At the same time, it should be noted that the relative atomic mass is multiplied by the number at the bottom right.

Take a look at this collection of mine.

There is a problem hi me.

Well, memorize the formula first. Doing the question is the key! The most important practice questions at the back of the book are to understand the example questions in the book before doing it. It works better.

The best way is to memorize chemical equations, and when you encounter a problem, you want to reflect, and then go to the set of formulas according to the given, the important problem solving methods you are learning now are the law of conservation of mass, and the breakthrough point is the equation.

NaOH + HCl = NaCl + H2O 40 100 * 16% xx = mass fraction of solute in solution = x (100 + 100).