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The following experimental phenomena are described incorrectly () A. Red phosphorus burns in the air and white smoke is produced B. Sulfur burns in oxygen and emits a light blue flame C. Bubbles are generated when the iron wire is inserted into dilute hydrochloric acid D. Purple litmus solution turns red after being filled with carbon dioxide
（7） 42-5 junior high school chemistry, what is the wrong description of these two particles? Give reasons There are two kinds of particles, the total number of protons in their nucleus is different, but the total number of electrons outside the nucleus is equal. The description of these two kinds of particles is wrong () A. It may be atoms and ions of the same element. B. it may be atoms and ions of different elements C. It cannot be atoms and ions of the same element D. it may be molecules and ions composed of the same element
A factory needs to use dilute sulfuric acid with solute mass fraction of 28% to remove rust for metal. The purchaser bought 2000ml98% concentrated sulfuric acid (density: 1.84g/cm3) from the chemical plant. How many kilograms of 28% dilute sulfuric acid can the worker master dilute it? How many liters of water do you need? My answer is: 2000mL × 1.84g/cm3 × 98％=3.6064kg 3606.4g÷（28％ × 1g/cm3）=12.88L But the correct answer is: 12.88kg 9.2L
When the solubility of a solute is s g at a certain temperature, the mass fraction of solute in saturated solution at that temperature () A. Greater than S% B. Equal to S% C. Less than S% D. Unable to judge
Relationship between mass fraction For example, the solubility of a solution increases with the increase of temperature, and its mass fraction is p, so its mass fraction decreases after the increase of temperature. I know this. Isn't the mass fraction of solute divided by the mass of solution? Then, when the temperature rises, only the solubility, solute mass and solution mass have not changed (assuming that water does not evaporate), isn't its mass fraction unchanged? How did it get smaller? This friend on the second floor doesn't understand what I mean. Let's mention the specific topic. If you want to change the mass fraction of potassium nitrate saturated solution at a certain temperature, reducing the temperature is also a way. Once the temperature is reduced, the solubility of potassium nitrate solution increases, but no new solute is added, but the maximum solubility of the solution changes. Isn't this process that the solute quality and solution quality haven't changed? How did the mass fraction change? It's not what the friend on the second floor said
Potassium nitrate solution with mass fraction of 20%, in which solute: solvent: solvent = at 10 ℃, the solubility of a substance is At 10 ℃, the solubility of a substance is 5g. At this temperature, in the substance saturated solution, solute mass: solvent mass: solution mass= Mass fraction of solution=
It is known that the mass fraction of nitrogen in the solid mixture of NH4NO3 and KH2PO4 is 28%, so the mass fraction of KH2PO4 in the mixture is () A. 20% B. 25% C. 85% D. 80%
What is meant by a sucrose solution with a mass fraction of 80g solute of 5%
How many grams of water need to be evaporated to concentrate 100g of sucrose solution with 10% mass fraction into 20% sucrose solution
13 g of zinc reacts with 100 g of dilute sulfuric acid to find: (1) the mass of oxygen produced (2) the mass fraction of dilute sulfuric acid
In 196 g sulfuric acid solution, 32.5 g zinc is added to just complete the reaction. Find the mass of hydrogen produced after the reaction?
A group measured the mass fraction of calcium carbonate in a limestone. 20g was taken as a nurse sample. 100g of dilute hydrochloric acid with a certain solute mass fraction was added to it
25g limestone containing 20% impurities fully reacts with 100g sufficient dilute hydrochloric acid (impurities do not participate in the reaction) Requirements: 1. What is the mass of carbon dioxide generated? 2. How many kilograms of calcium chloride are generated?
How many grams of carbon dioxide are prepared by fully reacting 100g limestone containing 80% calcium carbonate with 100g dilute hydrochloric acid (assuming that all calcium carbonate react) 1? What is the mass fraction of the solute of the dilute hydrochloric acid
What is the chemical equation between carbon dioxide and limestone
The experiment requires 13.2 grams of carbon dioxide, which is prepared by the reaction of calcium carbonate and sufficient dilute hydrochloric acid. How much calcium carbonate is needed
249.5 g of dilute sulfuric acid is added to a beaker containing 50 g of calcium carbonate and the reaction is just complete. Try to calculate the mass fraction of solute in the solution obtained after the reaction
Put 8 g of sodium hydroxide solid into 100 g of dilute hydrochloric acid and the reaction is just complete. Calculate the solute mass fraction of dilute hydrochloric acid
5.6g of pure iron completely reacts with 100g of dilute hydrochloric acid. Find 1 the mass of hydrogen generated; The mass fraction of solute in this hydrochloric acid solution emergency
Why do equal quality zinc powder and iron powder put into dilute sulfuric acid with equal mass and same solute mass fraction produce more hydrogen Why do equal quality zinc powder and iron powder add the same mass fraction of dilute sulfuric acid to produce more hydrogen
At T1 ℃, 5.6g iron powder was put into 100g copper sulfate solution to completely react   At T1 ℃, put 5.6g iron powder into 100g copper sulfate solution and filter after just complete reaction, so as to obtain: Mass of FeSO4 in filtrate The obtained filtrate was evaporated at a constant temperature to remove 66g of water and just turned into   Saturated solution at T1 ℃, find   Solubility of the solute at T1 ℃?
Put 5.6 g of iron powder into 80 g of copper sulfate and react exactly. Calculate (1) the mass fraction of solute in the original copper sulfate solution (2) the mass fraction of solute in the solution after reaction
Put zinc particles with a mass of 18 g into 40 ml with a density of 1.29 g / cm ³ After the reaction, take out the remaining zinc particles, wash and dry them, and weigh them to 4.9 G Q: A. how many liters of hydrogen are produced? (in this case, the density of hydrogen is 0.09 g / cm ³） b. What is the percentage concentration of dilute sulfuric acid? c. What is the percentage concentration of the resulting zinc sulfate solution?
What other information can you get about elements from the periodic table
What is the value of a in the fine structure formula of alkali metal atomic spectrum So what is its calculation formula?
After a certain amount of zinc is fully reacted with 100ml18mol / L concentrated sulfuric acid, the zinc is completely dissolved and the gas a33.6l (standard condition) is generated. Dilute the reaction solution to 1L and measure that C (H +) = 0.1mol (1) Composition of gas a（ (2) What is the volume ratio of the components in a（ (3) The mass of zinc consumed in the reaction is（ (4) The total amount of material that transfers electrons in the reaction is () moles? I'm counting 1.H2 SO2 2.H2:SO2=13:2 3.95.5g 4.3.4 moles
A small beaker containing hydrochloric acid of the same volume and concentration of the same substance is placed in each of the two plates of the tray balance. After adjusting the balance, add Fe powder and Zn powder of the same quality to the two beakers respectively. The following phenomena are impossible () A. At the beginning, the zinc adding end of the balance rises B. Finally, the zinc added end of the balance rises C. The final balance is still balanced D. At last, the iron adding end of the balance rises
Add 50ml 2mol / L H2SO4 solution to the mixture of Fe3O4 and Fe in a certain amount, and just dissolve the mixture completely under certain conditions, releasing 448ml (under standard conditions) gas. Add KSCN solution to the resulting solution, and there is no red. Then fully react with the mixture of the same mass with sufficient CO at high temperature, and what is the mass of iron?
The density of the mixed gas composed of carbon dioxide, hydrogen and carbon monoxide is the same as that of nitrogen at the same temperature and pressure. Then the volume ratio of carbon dioxide, hydrogen and carbon monoxide in the mixed gas is () A. 29：8：13 B. 22：1：14 C. 13：8：29 D. 26：16：57
High one chemical difference method
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