Solve a 9th grade chemistry problem and solve a 9th grade chemistry problem.

According to "take the filter residue gram in step 1, add a sufficient amount of dilute sulfuric acid to fully react with the filter residue, filter, wash and dry to obtain solid grams", it can be seen that the solid gram is activated carbon that does not react with dilute sulfuric acid, then: (1) the total mass of iron and ferric oxide in the gram of filter residue is;

According to the "gram of ferric oxide (the iron element in the filtrate has been converted into ferric oxide)", it can be seen that from 8g to 8g, it is due to the fact that iron becomes iron oxide, because 112g of iron can be changed to 160g of iron oxide, and the mass will increase by 48g, and now it has increased, indicating that there is iron originally, then there is iron oxide originally, and the 4g iron oxide is iron before deterioration. Therefore, (2) when the deoxidizer is not deteriorated, the mass ratio of iron powder to activated carbon is (::3; (3) The degree of deterioration of the oxygen absorber =

Answer: Step (1) dissolves the oxygen absorber solid in water, and filtration, washing, and drying the filter residue can remove the sodium chloride and water in the oxygen absorber.

The filter residue 8g in step 2 is a mixture of iron powder and activated carbon. After adding a sufficient amount of dilute sulfuric acid, the iron powder reacts completely, and the solid obtained is activated carbon.

Therefore, the total mass of iron and ferric oxide in the gram filter residue (from step 3, it can be seen that the number of moles of iron in 8g of ferric oxide is the same as the number of moles in the deoxidizer. The mass of iron in the oxygen absorber: 56*8 (56*2+16*3) = the mass ratio of iron powder to activated carbon when the oxygen absorber is not deteriorated.

Solution: The number of molecules with co is x

The number of molecules of mol,H2 is y

mol, there is. co

o2co21mol

O2H2O because x+y=n

So the number of oxygen molecules that require oxygen is.

Therefore the answer is chosen. c

The actual quality of sodium chloride to be weighed is. The actual weighing should be the left and right code, and now it is reversed, indicating that the mass of the object obtained is the weight mass minus the number of the code (originally added, the position is reversed, and the mass of the code was originally added to the sodium chloride, so it is relatively smaller). So the actual to sodium chloride because there's water.

So the actual mass fraction c(nacl)=

If you want to be accurate to one decimal place, you should choose A

Answer: a

Analysis: The mass of NaCl required to prepare a 50g NaCl solution with a mass of NaCl: m(NaCl)=50*

The mass of water required to prepare 50g of NaCl solution with mass is: m(H2O) = so the weight mass in the tray m1=3g; Traveling code mass m2 = in the use of pallet balances, left = right + swimming.

Therefore, the actual NaCl mass (i.e., right disk mass) according to the method described in the question is: M'= Therefore, the mass fraction of the solute of the NACI solution prepared by the student is actually (please correct the inappropriateness).

The reason is called.

It is actually weighed out due to the wrong left and right.

is = is a

Weight + code = material mass Now it is reversed, and it becomes a game code + material mass = weight It was originally needed to be a game code, so the weight is 3g so NaCl only.

The answer should be A.

According to the question stem, it can be calculated that the mass of NaCl should be measured for the water used, so 3g weights and swimming codes should be used. But because the placement is upside down. The mass of the drug minus the mass of the code is equal to the mass of the weight, and becomes the mass of the called NaCl plus 2 times the mass of the code is equal to the mass of the weight.

That is, it can actually be called. Divide by (to get the answer.

The molecular weight of water is 18, the mass is 9, there are n, the molecular weight of sulfurous acid is 64, the mass is 64, there are 2n.

Note: SO2 should be called sulfur dioxide.

The ratio of the actual mass of the molecule to the relative molecular mass is constant, and the relative molecular mass of water is 18,

First, measure the mass m1 of the empty cup

Then measure the mass m2 of the edible oil in the beaker

The quality of the edible oil is m2-m1

The syringe has a scale to measure the volume v

Then the density of edible oil is (m2-m1) v

The syringe can function as a graduated cylinder. 1 compartment is usually 1 ml. Use the balance to measure the weight of the empty cup first.

Then pour 1 bar of cooking oil into the cup, and then use the balance to measure the weight of the cup to add oil. The weight of the refueled cup minus the weight of the empty cup is equal to the weight of the oil. The weight of the oil divided by the volume of the oil is equal to the density of the oil.

The mass of 100kg NH4NO3 nitrogen-containing element is 100kg*28 80=35kg

NH4HCO3 has a mass of 35 kg (14 79)=

: The mass of the sulfuric acid solution in this reagent bottle is:

In order to prepare 200g of dilute sulfuric acid with solute mass fraction, what is the mass of this concentrated sulfuric acid?

Solution: Let the mass of 98% concentrated sulfuric acid be x.

x×98% =200g×

x = 40g

Answer: Slightly. How many grams of hydrogen can be produced by taking a sufficient amount of dilute sulfuric acid and fully reacting with 13g of zinc?

Let the mass of hydrogen that can be produced be y

zn+h2so4=znso4+h2

13g y solution y=

A: Hydrogen can be withdrawn.

The mass fraction of concentrated sulfuric acid should be given, I think it should be 98%, because the concentrated sulfuric acid bought in the laboratory is basically 98%.