A few calculation questions about metals and their compounds

I'm glad to answer for you, let's take a look at the question first, both of these questions need to use the extreme value method, the first question: react with a sufficient amount of hydrochloric acid to get hydrogen, if it is four pure metals, then na needs, mg needs 6g, al needs, iron needs 14g, and we look at the question and find that the mixture is 12g, which means that in the mixed metals, one of the metals that generate hydrogen should be less than 12, and the other should be greater than 12, and the two will be balanced, obviously only iron is greater than 12, so it is d answer. The second question, similar to the first question, this time is the hydrogen obtained, which requires pure metal to produce hydrogen, one should be greater than 10, and the other should be less than 10, let's look at the answer, a answer:

12-9, B answers, 12-28, C answers, 9-28, D answers, , obviously, A, C is correct. Any questions? I hope I can help you and wish you progress in your studies.

1. Let's first calculate the quality required for the release of NA, MG, and AL. The amount of hydrogen is consumed by the reaction of Na, Mg, and Al, respectively, and the amount of Na, Mg, and Al substances is converted into mass, which is less than the mass of the alloy is 12, and the reaction of iron and acid requires the consumption of 14g, which is greater than 12g, and the size is uniform, and there must be iron. 2. Under the standard condition, the amount of the converted substance is 10gmg and the gas released by the reaction with dilute sulfuric acid is:

10 24 = 5 12mol 10gal: 10 27 , so a can. 10gfe：

10 56 = 5 28mol and mg is 5 12, so b can't. In the same way, al in c , fe is less than, so it can. 10gzn：

10 65 = 2 13, mg is also less than, d no.

The sodium is, released.

molh2, is hydrogen, the mass of the solution is, where NaOH is the sodium oxide, does not release gas, NaOH is the sodium peroxide, releases oxygen, that is, NaOH is the sodium hydroxide 4g

No gas is released, 100 + 4 = 104g, NAOH is 4g. It can be seen from the comparison that sodium oxide = sodium peroxide and sodium hydroxide, so choose b

The answer is c, as can be seen from the figure, the more active the metal, the shorter the reaction time, knowing that x is magnesium, y is zinc, and z is iron.

Putting three parts of dilute hydrochloric acid with the same solute mass fraction does not say that hydrochloric acid is equal, but Z produces more hydrochloric acid, which means that hydrochloric acid is consumed a little more.

XY produces as much hydrogen as it does, indicating that there is a surplus of magnesium and the zinc reaction is finished.

The angle between ADXYZ and X-axis is selected as the reaction rate, and the larger the angle, the faster the reaction. Thus, x should be magnesium, y is zinc, and z is iron.

If there is an excess of acid, then X should be the highest, followed by iron, and last by zinc.

And z is the highest, so the acid is not excessive; Magnesium must react completely. Pick D

The slope of the slash indicates the speed of reaction.

According to the metal liveliness, it can be known that mg is more active than Zn and more active than Fe.

So A is correct.

Because it is the same mass of magnesium, iron, and zinc.

The amount of gas produced by Mg and Zn is the same, indicating that the HCl reaction is completed in the two reactions. mg must be overdosed.

Zn and Fe may be reactive.

The maximum amount of hydrogen is generated according to Z, so B is correct.

c is incorrect.

(1) As can be seen from the table, there are 8 gcu in the sample (from groups 3 and 4, it can be seen that the remaining 8g is unreacted at the end) 12gzn

8g/20g=40%

2) There are 12gzn involved in the reaction Let the final co-generated gas x g zn + 2HCl = znCl2 +H2 65 212g xg65 2=12g xg get x=24 65 to generate gas 24 65 g (approx.

Analyze ideas.

1) Copper and zinc, add dilute hydrochloric acid, then the reaction with dilute hydrochloric acid is zinc.

2) Observe **, the final remaining amount of solid is always 8, combined with 1), then there are 12g of zinc and 8g of copper in 20g, and the mass fraction is calculated by yourself.

3) With the quality of zinc, is the amount of hydrogen released when it is completely dissolved?

The question should focus on the analysis process, and it is useless to just get an answer.

Solution: The mass of oxygen produced is.

Let the masses of CO2 and H2O be x and y, respectively

2co2+2na2o2=2na2co3+o2↑x 32x/88

2h2o+2na2o2=4naoh+o2↑y 32y/36

x+y=32x/88+ 32y/36 =

x=y=The mass of CO2 in the compound gas is.

Oxygen. There is oxygen i.e. carbon dioxide and water according to the chemical equation) and then the equation is listed.

Solution: The mass of oxygen produced is.

The molar masses of oxygen with CO2 and H2O are x and y, respectively

2h2o+2na2o2=4naoh+o2↑y

2co2+2na2o2=2na2co3+o2↑x

x= y= mass of CO2 in gas is.

1、n(co2)=

m(c)=c%=2, the average molar mass of the mixture m(average)=

If m(m2CO3)=, then m(m)=

If m(mhCO3)=, then m(m)=

So the alkali metal element is potassium element, and the chemical formula of two carbonates: K2CO3, KhCO33HCO3-+H+=H2O+CO2

1 1xx=

n(hcl)=

c(hcl)=

%=(5*10^3*12*10)/

2.Let the salts be XHC3 and X2CO3

then the molecular weights are (61+x) and (60+2x).

As can be seen from the figure, there are 12 units of x2CO3, 8 units of xHCO3 3*10 -3mol 2*10 -3mol, 3*10 -3*(60+2x)+ 2*10 -3*(61+x)=x=39

are two salts of the K element.

c=8*10^-3/(32/1000)=

According to the conservation of element mass, the mixture of zinc powder, aluminum powder and magnesium powder is completely reacted with a certain quality of dilute sulfuric acid to obtain 11g of zinc sulfate, aluminum sulfate and magnesium sulfate mixture, and the mass of sulfate is According to the chemical formula of sulfuric acid, it can be seen that the mass ratio of hydrogen element to sulfate is 2:96 Hydrogen element finally exists in hydrogen, so the mass of hydrogen produced is 2*

The use of conservation of mass is the mass of sulfate, which is the amount of sulfate substance.

So H2SO4 is so H2.

Got it ok!!

a Because the mixture has 11g, it can be seen that the sulfate ions in the mixture are.

That is, there is so the sulfuric acid that participates in the reaction is also the H2 that is generated.

Simple method: , that is, the mass of sulfate in the reaction product, from which the sulfuric acid reaction mole is obtained, and the gas mole is generated, and the gram is selected.

Answer your question first: answer on 1When calculating the concentration of sulfuric acid, it is directly calculated by experiment 3, because looking at the ratio of the amount of hydrogen produced and the mass ratio of the added powder, the powder in experiment 3 is excessive, and it is only necessary to do so.

Last question: When fully reacted, 100ml of sulfuric acid gives hydrogen, Fe H2 (reaction equation).

n(fe)=n(h2)=v/vm=

m(fe)=n(fe)*m（fe)=

m(c) = n(c) * m(c) = *12 = ratio of the amount of matter according to the first question).

m total = m (fe) + m (c) =

When the sulfuric acid is not reactive, m<

At this point, the remaining powder is c, so, n(c)=n(fe) 50=

The remaining powder mass is: m(c)=n(c)*m(c)=(*12=3(m-50624) 700g

When the sulfuric acid is completely reactive, m

At this time, the remaining powder is a mixture of C and Fe (if the powder is divided into two parts, only C is left after the reaction, and the other part does not participate in the reaction).

The remaining powder mass is: (

Not participating in the reaction part of the remaining c) before the complete reaction

The answer is 1When calculating the concentration of sulfuric acid, directly use Experiment 3 to calculate, why.

Because the quality of the steel powder in the experiment is proportional to the gas generated, it means that the sulfuric acid is excessive, and the steel powder is completely reactive.

Only the mass of steel powder added in experiment 3 was disproportionate to the gas produced compared with the previous two experiments, and the sulfuric acid in experiment 3 was completely reacted and the steel powder was excessive.

Therefore, the amount of sulfuric acid is calculated using Experiment 3, and then the concentration (volume is known) is calculated

The last question asks for a detailed explanation.,I don't understand.。。

Steel powder contains carbon, which does not participate in the reaction, and finally in the remaining solid;

Excess steel powder is also left in the remaining solids.

Therefore (m+ content Fe molecular weight = sulfuric acid equivalent, the remaining solid mass is (m+ content).

M+ content Molecular weight of Fe 》When sulfuric acid equivalent, the remaining solid mass is sulfuric acid equivalent number * Fe molecular weight Fe content * (1-Fe content) + (M + sulfuric acid equivalent number * Fe molecular weight).