Chemistry calculation questions in junior high school will not help

Carbon dioxide can be rolled out with 60 grams of carbon, which are all derived from citral, 72g of water and 8 grams of hydrogen, which is burned in oxygen.

Citral+O2->CO2+H20

c%=12/44*220/76*100%=h%=2/18*72/76*100%=

o%=m=46 grams of formic acid contains 2 grams of hydrogen, and the hydrogen content of ethanol is 6 46, so in proportion, it is 46 3, which is approximately equal to.

3.Formic acid is a monobasic acid that releases one hydrogen ion, so the mol number containing hydrogen ions) 2, the mol number of hydrogen is obtained, and then *1 is the mass of hydrogen.

hcooh->1/2h2

200*10% mm=

1.The elements contained are c, h, o.

c:h:o=6:1:8

2.Solution: H mass in HCOOH: 2g

Because the mass of C2H5OH is equal to the mass of H in HCOOH, the mass of H in C2H5OH is also 2G

2 6 46 approx.

Ribose is an indispensable substance for human life activities, the relative molecular mass of ribose is known to be 150, which contains 40% carbon, hydrogen, and the rest is oxygen, and the chemical formula of ribose is inferred by calculation.

An ironmaking plant uses magnetite ore containing 20% impurities (the main component is ferric tetroxide) to make iron, how many tons of iron can be smelted theoretically with 500t of such ore?

150*40%=60=12 (atomic weight of c) *5 (molecule contains 5 c) 150*atomic weight)*10

150*(100%-40% atomic weight)*5

So the chemical formula of ribose is C5H10O5

You can buy a Tianli 38 sets, don't buy that kind of special, it's all a spelled question, and there are a lot of mistakes. It's also unreliable on the Internet, and it can you off to death....

Isn't it in the textbook? It's very detailed.

Mass fraction = (solute mass solution mass)*100%.

1. The group carries the air and collapses into the solute.

50*a%+x=(50+x)*2a%

x=50a/(100-2a)

2. Evaporative dissolving concealer.

50*a%=(50-y)*2a%

y=25g

Question 1:

1)m=ρν=

280g×50%=m×20%；m = 700g 700g of dilute solution with a solute mass fraction of 20% can be prepared.

na2co3+ba(oh)2====2naoh+baco3↓

x= y=8g z= \

NaOH in the mixture

The mass of the substance Na2CO3 participating in the reaction in caustic soda is grams.

The purity of this caustic soda is: (4g) 100%=

The total mass of NAOH is: 4G+8G=12G; The mass of the solution is:

The mass fraction of solute in the resulting solution after the reaction is: (12g 120g) 100% = 10%.

Question 2: I can't see the picture clearly.

It is possible to prepare a dilute solution with a solute mass fraction of 20% x grams.

Then: 200*

x = 700 grams.

A must be a base, and a can be introduced as ba(oh)2

So the mass of naco3=

4 NAOH = 8g generated

8g/(

1)m=ρν=

280g×50%=m×20%；m = 700g 700g of dilute solution with a solute mass fraction of 20% can be prepared.

na2co3+ba(oh)2====2naoh+baco3↓

x= y=8g z= \

NaOH in the mixture

The mass of the substance Na2CO3 participating in the reaction in caustic soda is grams.

The purity of this caustic soda is: (4g) 100%=

The total mass of NAOH is: 4G+8G=12G; The mass of the solution is:

The mass fraction of solute in the resulting solution after the reaction is: (12g 120g) 100% = 10%.

Question 2: I can't see the picture clearly.

The solute mass fraction of 20% dilute solution was set to be X grams.

Then: 200 * x = 700 grams of a base, and a is ba(oh)2

Mass of mnaco3 =

4 NAOH=8G8G (

1.(1) It is possible to prepare a dilute solution with a solute mass fraction of 20% x grams.

Then: 200*

x = 700 grams.

2) Don't understand the meaning?

2.Can't see the picture? Write it more clearly.

What a master! Awesome!

1. Establish a salt field and use Taihe Zen to summon Yuyang energy to evaporate naturally.

mgcl2 + ca(oh)2 ==mg(oh)2 + cacl2150* x

The solution is x=