A few chemistry questions to help! Extra points for getting it right!!

The mixture is 3) air.

8) Hydrogen peroxide solution.

9) Liquid air.

14) Sea water.

The purity is 1) water.

2) Phosphorus pentoxide.

4) Potassium permanganate.

5) Hydrogen peroxide.

6) Manganese dioxide.

7) Sulfur powder 10) Carbon dioxide.

11) Aluminum 12) Alumina.

13) Sulfur dioxide.

15) Oxygen.

Oxides are 1) water.

2) Phosphorus pentoxide.

5) Hydrogen peroxide.

6) Manganese dioxide.

10) Carbon dioxide.

12) Alumina.

13) Sulfur dioxide.

1.The mixture is (3,8,9,14), the pure is (1,2,4,5,6,7,10,11,12,13,15) and the oxide is (1,2,5,6,10,12,13).

2.Use a wooden strip with sparks to reach into a gas cylinder containing carbon dioxide, and the wooden strip goes out3Neon

4.After a few bubbles, it is estimated that the air in the air duct has been exhausted and begins to collect5The unplugged (or unplugged) cotton at the mouth of the test tube allows the potassium permanganate powder to be carried into the water by oxygen6

Physical Changes**: Pressure cooker due to excessive internal pressure**; LPG tanks are heated ** Slow oxidation: copper coins rust; The iron pot is rusty; The bicycle rim is rusty.

1.The mixture is (3, 8, 9, 14).

The pure substance is (1,2,4,5,6,7,10,11,12,13,15) and the oxide is (1,2,5,6,10,12,13)2A wooden strip with a spark is inserted into a gas cylinder containing carbon dioxide, and the wooden strip is extinguished, indicating that CO2 does not support combustion.

3.Neon ne4After a few bubbles, it is estimated that the air in the air duct has been drained and begins to collect.

5.The cotton at the mouth of the test tube is not plugged (or not plugged) so that the potassium permanganate powder is carried into the water by oxygen.

6.Physical Changes**: Pressure cooker due to excessive internal pressure**; LPG tanks are heated ** Slow oxidation: copper coins rust; The iron pot is rusty; The silver ring is blackened.

The first floor and the second floor are all good. Copy of the third floor! Despise! I don't want to say anything more about them being right.

But when it comes to the second topic: 2What else can be used to verify carbon dioxide with clarified lime water?

I don't know how to say it, the answer on the second floor is actually meaningless. Non-flammable gases are easy to find. If you put a wooden strip with sparks in it, the extinguishing of the wooden strip does not mean that there is carbon dioxide inside, but it may also be other gases such as nitrogen.

I don't know what grade you have, but the CO2 test is mainly through the clarified lime water.

I don't know if there's a particularly good way to do it. If interested, you can also measure the density of the gas or the molecular mass of the gas. Dizzy.

Then there is the fourth question: 4When is the right time to collect oxygen by drainage?

The answer on the second floor is not bad either. However, it is estimated that the statement that the air in it is exhausted is not good.

It is generally necessary to place the catheter in the sink and wait until it bubbles evenly to start collecting, because it is generally believed that the time when even bubbles appear is when the air is exhausted.

Soluble in water, weakly acidic.

Neon. When bubbles pop up continuously.

Unstuffed cotton.

Cl2 can replace br2. The results indicated that Cl2 was more reducible than Br2, i.e., non-metallic activity was stronger. The same goes for i2>s br2>i2

So Cl2>br2>i2>s

Example 1:

Analysis: This question examines the concepts of redox reactions.

CaCo +2HCN = Ca(CN) CO + H Co (note that the CO carbon element in the product comes from CACO, and its valency does not change before and after the reaction), that is, the valency of hydrogen element decreases and the valency of carbon element increases, so HCN is both an oxidant and a reducing agent, Ca(CN) is an oxidation product, and H is a reduction product.

Answer: b, c.

Example 2: A: Correct.

B: Hydrogen reacts with oxygen, and hydrogen is the reducing agent.

C: Elevated electrolyzed water O.

D: Correct. For example, Cu + 2 Fe = 2 Fe Cu, Fe is reduced to Fe valency.

So the answer is AD

Example question 3 answer: Answer: If the three reaction tubes with sufficient amount of Cu powder, C powder and Cuo powder are arranged and combined, there are 6 situations in total, and they can be solved one by one, but it is quite time-consuming and laborious.

For example, divergent thinking can be used to reduce O2, CO2 and H2O to CO and H2 from reducing agents Cu powder and C powder; The oxidant Cuo can be considered from the perspective of oxidizing CO and H2 to CO2 and H2O, and a new angle can be found and a new solution can be found

It is not difficult to find that no matter how the three reaction tubes of Cu powder, C powder and Cuo powder are arranged, O2 must no longer exist, and there are CO2, H2O or CO and H2 in the exhaust gas.

Answer: Impossible Yes, O2 does not.

Is this an exaggeration? These are all basic topics... 150 points... I thought it was a competition...

2Na2SO3+O2==NaSO4 NaSO4+BACl2==2NaCl+BaSO4 (precipitation symbol).

NaSO3+BACl2==NACl2+BASO3 (precipitation symbol).

BaSO3 + 2HCl = = BACl2 + SO2 (gas symbol) + H2O

Na2SO3 is oxidized to Na2SO4, and BAC2 is added dropwise to produce a white precipitate, and HCl is added, and the precipitate is insoluble.

2br+ch2=ch2===ch2brch2br bromine water increases the mass of ethylene.

This number is not ideal, and it cannot be counted as an integer.

You just have to do it this way.

The mass is 38% * 50 * 44 73 = , the volume is 19 73 *, if you don't learn the molar volume, use the density you give to calculate the volume, 550 *, 550-55 = 495g