What is the amount of a substance

If you are a freshman in high school, your chemistry book should have n=a*aa (Afergadro's constant) is that the amount of matter is equal to the number of particles multiplied by Afergadro's constant (which is a fixed unit).

The quantity of matter is a physical quantity that represents a set of particles containing a certain number of particles.

The amount of a chemical substance in the first high:

1. Take out any volume of solution from the quantity concentration solution of a certain substance, the amount and concentration of the substance remain unchanged, but the amount of solute substance is different with the change of the volume of the solution.

2. At the same temperature and pressure, any gas in the same volume contains the same number of molecules.

3. The scope of application of the molar volume of the gas is a gaseous substance, which can be a single gas or a mixed gas.

4. The quantity of matter is measured by microscopic particles.

5. The mass of a substance per unit of substance is called the molar mass of the substance.

The selection of volumetric flasks must indicate the specifications, which should be equal to the volume of the solution being prepared.

If not, a volumetric flask slightly larger than this volume should be selected, such as a 500mL volumetric flask should be selected for the preparation of 500mL of 1mol·L-1 NaCl solution, if 480mL of the above solution is required, because there is no 480mL volumetric flask, a 500mL volumetric flask should also be selected, and the amount of solute required for the 500mL solution should be calculated according to the preparation of 500mL solution.

The method of checking whether the volumetric flask is leaking before use is: inject a small amount of water into the volumetric flask, plug the glass stopper tightly, press and hold the stopper with your fingers, press the bottom of the bottle with the other hand to reverse the volumetric flask, observe whether there is liquid oozing out at the cork after a period of time, if there is no liquid seeping, put it right, rotate the glass stopper 180°, and then reverse the observation.

n The amount of a substance in mol moles.

m molar mass unit g mol gram per mole is the molar mass without a unit, and the value is the same.

na Afergadro's constant is the specific number of one mole.

m can represent the mass of an atom or something like that.

Once you understand the meaning, you will naturally forget it.

First of all: the unit of quantity of matter mole, abbreviated mole, symbol mol, n = n naThe mass possessed by a substance per unit of quantity is the molar mass, for example:

The molar mass of mg is 24g moli.e. numerically equal to its mass, 24, the quantity of matter (n) mass (m) and the molar mass mRelationship:

n=m/m., unit: m is g, m is g mol

So n is mol

For example: What is the amount of sulfuric acid?

Answer: n = result as: , the mass of sodium carbonate is? m = number of particles (n).

m denotes the mass of the substance, n denotes the quantity of the substance, and m denotes the molar mass m=n*m

The relative molecular mass of Zn is 65, then the amount of the substance of Zn is HCI is Znci2 is H2 is, mass = quantity of substance * relative molecular mass.

Solution: n(h2) = =

Let xmolzn,ymolHCl participate in the reaction to produce zmolznCl2, then:

zn + 2hcl = zncl2 + h2↑1 2 1 1xmol ymol zmol

1 x = 2 y =1 z = 1 x = y= z=

i.e.: the quantity analysis of the substance of zn hcl zncl2 h2 is:

m(hcl) = * =

m(zncl2) = * 136g/mol =

The mass ratio of Na, Mg, and Al is 23:12:9, so the molar ratio of the three elements is (23 23).

1 3 = 6:3:2, that is, the ratio of the mass of sodium chloride, magnesium chloride and aluminum chloride.

Let NaCl have 6x mol, magnesium chloride has 3x mol, and aluminum chloride has 2x mol

Then 6x+3x*2+2x*3=

x=, 3x=, 2x=

Quality is grams.

1) Because the mass ratio is m(na):m(mg):m(al)=23:12:9, the mass ratio of the three elements of matter is.

n(na):n(mg):n(al)=(23g/23g/mol):(12g/24g/mol):(9g/27g/mol)

2) Since the quantity of the substance has been found in the first question to be 6:3:2, but now it is for the chlorine atom, so let the quantity of the substance of the mixture be x moles, then the amount of the substance of NaCl is (1 2)X, MgCl2 is (1 4)X, and AlCl3 is (1 6)X

Now let's look at the chlorine atom, since the three chlorides contain different numbers of chlorine atoms, the amount of chlorine atoms in the mixture is n(cl)=(1 2)x*1+(1 4)x*2+(1 6)x*3=

After solving x=, we now know that n(NaCl)=, n(mgCl2)=, n(alCl3)=, and then multiply the molar mass respectively to know the total mass of the mixture.

M (Total) = M (NaCl) + M (MgCl2) + M (ALCl3) = Okay, the result is your own.

The first of the three elements has a relative molecular mass of 23 12 9, so the ratio of the amount of matter is 1:1:1

The second chlorine atom is , then the total amount of the three substances is , and since the ratio of the three elements is 1:1:1, the ratio of the three substances is 1:1:1, respectively.