Junior high school chemistry question 7, 7th grade chemistry question

1) Suppose the tablet is pure calcium carbonate, the mass of each tablet is 40 50=, and the highest calcium content is:, so the calcium content of the target is wrong.

2) The values of the four reductions in total mass are: average reduction in CaCO3 + 2HCl == CaCl2 + H2O + CO2 100 mass reduction of 44

x Mass reduction.

The solution is x = 10 tablets total, so each tablet contains calcium carbonate.

The calcium content of each tablet is:

It is recommended that the label be changed to:

Calcium content: grams of calcium per tablet or calcium carbonate per tablet.

1) The calcium content is wrong, obtained from "50 tablets per bottle, weighing 40 grams", each tablet weighs grams, the amount of calcium carbonate is 100, and the calcium content is 40, assuming that it is all calcium carbonate, and the calcium content of each tablet will not exceed grams (.

2) The mass of calcium carbonate in 10 calcium tablets = (, the amount of calcium carbonate in each calcium tablet is grams. The calcium content in each calcium tablet is = grams.

It is recommended that manufacturers talk about calcium content as "calcium content: calcium grams per 10 tablets".

First of all, correct that there is a chemical formula wrong CaCl2

The amount of CO2 that is reduced before and after the reaction is the mass of CO2, so it's simple.

CaCO3+2HCl=CaCl2+H2O+CO2X 44 The solution is x=

The total weight of 10 calcium tablets is grams, and the weight of each tablet is grams, and the calcium content is grams.

The calcium content is wrong, otherwise correct. The following numbers correspond to CO2.

1) Error; Each bottle has 50 tablets with a total weight of 40g, that is, the quality of each tablet is. Suppose the tablet only contains calcium carbonate, the molecular weight of CaCO3 is 100, of which the calcium is 40, if it is calcium carbonate, then it contains only calcium, it cannot be.

2) The first question: CaCO3+2HCl=CaCl+H2O+CO2 The gas formed by the law of conservation of mass is, that is, in the reaction formula, CaCO3+2HCl=CaCl+H2O+CO2

x can be calculated as calcium carbonate, which is the calcium carbonate content of 10 tablets, and the calcium carbonate in each tablet is the second position: caco3 ca

y can be calculated as . Each tablet contains calcium.

It is recommended that the manufacturer change the calcium content in each tablet to contain calcium carbonate.

The last question I don't understand is do you want to know whether the valency of the atomic cluster is the valency of the atomic cluster or the valency of the metal cluster, which is the valency of sulfate-2 and the valence of hydroxide-1.

Turn left to start the spiritTurn right.

1.In winter, tap water will burst the water pipe due to freezing, indicating that the void between molecules in ice is larger than in water, which indicates that the main reason for the change between the three states of matter is due to the change in the distance between molecules

2.The following statement is correct (a).

a.The iodine particles placed in the bottle disappeared because the iodine sublimated into iodine vapor.

b.In early spring, the white fog on the river surface is water vapor - no, it is a small water droplet wrapped in dust, water vapor, and you can hardly see the drops!

c.The frost that is common in early winter mornings is formed by the solidification of water vapor - condensation.

d.In the summer, the popsicle is so teased that the popsicle is emitting "white gas", which is the water vapor that evaporates after the popsicle melts - the water vapor in the air is cold.

During the Spring Festival, the driest place in China: the center of the Turpan Basin, there is a rare rime phenomenon, which is a milky white crystal formed by supercooled water vapor in the air on the surface of an object, and the process of changing the state of matter has to release heat.

1. Caused by different gaps between molecules.

2, A3, Ninghua release.

1.Hydrogen peroxide = water + oxygen.

2.Potassium permanganate = potassium manganate + manganese dioxide + oxygen.

3.Charcoal + Oxygen = Carbon Dioxide.

Both 1 and 2 are the reaction of one substance to produce two or more substances, which is a decomposition reaction.

3 is the reaction of two substances to form a substance, which belongs to the chemical reaction.

1. Remove carbon dioxide from the gas mixture.

2. Verify that there is carbon dioxide in the original mixed gas, and prove that the carbon monoxide in the original mixed gas reacts with copper oxide to form carbon dioxide.

3, anhydrous copper sulfate in a turns blue, which proves that there is water in the original mixed gas, and B becomes turbid 4, E The final discharged gas may contain toxic carbon monoxide gas that needs to be collected or treated.

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