How do you measure the density of a gas? What is the formula for calculating gas density?

First find a rubber stopper just enough to plug the mouth of the glass bottle, make a hole in the stopper**, and insert the metal tube or glass tube into the hole tightly (the rubber stopper can be immersed in hot water when the hole is small, take it out after a few minutes, insert the tube into the piercing while it is hot, and tighten it after cooling), and plug the stopper tightly. Place the rubber catheter over the metal tube and weigh the total mass of the bottle, clip, and catheter with a balance. Remove the bottle and inflate it from the catheter with a pump.

After a dozen shots, clamp the rubber catheter tightly with a clamp, pull out the pump, place the bottle on the balance again, and increase the milligram weight until the balance is rebalanced. The added milligram weight is the amount of air that is added to the bottle. Record the air quality m.

Remove the bottle. After filling the graduated cylinder with water, place the graduated cylinder upside down in a basin of water. Insert the mouth of the rubber catheter attached to the bottle into the graduated cylinder, loosen the clamp, and collect the air filled into the bottle by draining the air and taking the air.

After there are no bubbles in the measuring cylinder, move the graduated cylinder up and down so that the water surface in the cylinder is level with the water surface in the basin (so that the air pressure in the graduated cylinder is one atmosphere). Observe the scale of the graduated cylinder and record the volume v of the air in the cylinder. According to the density formula, find the density of air at room temperature and pressure.

1. The air should not be too much at each time, if it is too much, it is not easy to find the large container when collecting air, and it is difficult to measure the volume of air at room temperature and pressure; The air should not be too little, too little is inconvenient to increase the weight when weighing. After testing, it is generally advisable to hit ten times. If you choose another type of pump, fill the cylinder with water first, then invert the basin, use the pump to inflate the cylinder, the air after drainage does not exceed the full scale, note the number of inflats, and fill the bottle with the same number of times.

2 The key to this experiment is to do a good job in this experiment by not leaking the connection between the bottle mouth and the stopper, and the plug and the catheter. After plugging the stopper and catheter, immerse the bottle mouth in water, inflate it with a pump, and see if there are bubbles coming out of the bottle mouth. If there is an air leak, wipe it dry and heat it with butter or petroleum jelly and pour it into it until it does not leak.

3 Because the air quality is very small, milligram weights should be used, and the balance should be carefully adjusted. 4 If there is no large glass bottle, you can find a hard plastic bucket or metal bucket instead, and there should be no obvious change in the volume before and after inflation. Because the volume becomes larger after inflation, the buoyancy of the air on the container becomes larger, and the air quality weighed is smaller, and the density of the air cannot be measured. Thank you!

When measuring, you should pump up first, then weigh, and weigh again after deflating. The first minus the second is the quality of the release. Instead of weighing first, then pumping and then weighing, because you can't guarantee that much gas will be released.

The formula for the density of a gas in an ideal state =pm nrt.

The density of air in a standard state (a standard physical atmosphere, 0 degrees Celsius) is kilogram cubic meters. The density of air is directly proportional to the pressure and inversely proportional to the absolute temperature. So air density = actual pressure standard physical atmospheric pressure) * (273 actual absolute temperature) absolute temperature = Celsius + 273.

Characteristics of gas density:The high-density atomic gas is cooled to a very low low temperature, which can be divided into bose gas and Fermi gas according to its statistical properties, and other phases can be referred to the phase list. The properties of the gas are between that of a liquid and a plasma, the temperature of the gas does not exceed that of the plasma, and the lower temperature limit of the gas is the degenerate quark gas.

The formula for calculating the gas density is as follows: =m v=nm v=m*n v=pm rtn v=p rt The formula for calculating the ideal gas density =pm rt: density, p:

Gas pressure, r: constant of state, t: absolute temperature, the formula for calculating the density of the mixed gas, according to the ideal gas equation of state pv=nrt; i.e. pv=mtr m, because m= v; So:

pm trd= (mixed) a) = m(mixed) m(a)m denotes the molar mass of the substance.

The formula for calculating the density of the gas is as follows:

m vm stands for: the mass of the object.

v denotes: the volume of the object.

Since gas molecules often move in containers, their mass is generally expressed in terms of density. Density is the mass per unit volume and is also the reciprocal of specific volume. There is a wide range of variations in the density of gases because when constrained by pressure or volume, gas molecules can get closer to each other.

The change in density is called compressibility, and the density, pressure, and temperature of the gas are all state variables, and the changes in the process will follow the laws of thermodynamics. In the case of static gases, the density of the gas is the same throughout the container. Density is a scalar quantity, and in the case of a fixed mass gas, the density is inversely proportional to the volume of the container.

Density and buoyancy1. The object is in water.

Object < water, where the object floats (floats).

Object = Water, the object is suspended.

Object》 Water, the object sinks to the bottom (sinks).

2. For any liquid.

Objects < liquids, objects float (or float).

Object = Liquid, the object is suspended.

Object liquid, the object sinks to the bottom (or sinks).

When the object is liquid (the object floats or is suspended).

The volume of the object in water: The volume of the object = The volume of the object: The liquid when the object = The volume of the object in the water when the water (object) is suspended: The volume of the object = 1:1

Calculate the gas density.

Using the gas equation pv=nrt, p is the pressure, v is the volume, n is the number of moles, r is the constant, and t is the absolute temperature.

And n = m mmol, m is the mass, and mmol is the molar mass.

So PV=MRT mmol

And density = m v

So =pmmol rt, so, as long as the pressure, molar mass, absolute temperature are known, the density of the gas can be calculated.

Precautions1. Because the density of the air is related to the pressure, when the gas is collected by the drainage method, it is necessary to make the water surface inside and outside the beaker flat, so as to ensure that the pressure of the air in the cup is the same as the pressure of the ambient air.

2. Since the container contains compressed air, it must be slow to deflate to prevent the gas from rushing to the outside of the beaker.

3. This experiment also obviously shows that air has mass.

The weight (mass m) of a substance per unit volume (v) is called the density of the substance (d), i.e., d=m v.

Gases are light in weight and low in density due to the large distance between molecules. As the volume of the gas changes with the change in pressure and temperature. As the pressure increases, the volume of the gas decreases and the density increases.

For example, the density of air at atmospheric pressure (d) is, and when pressurized to 5 atmospheres, the volume decreases by 5 times, and the density increases by 5 times.

Gas density - standard density.

Under standard conditions ATA) the weight of 1L gas is its standard density, which can be found in the table below.

Standard density table for various gases.

Name of gas Density (g l).

Air: hydrogen, nitrogen, nitrox, carbon dioxide.

Carbon monoxide 1

Xenon-radon gas density - relative density.

In order to facilitate the comparison of the weight of various gases, the ratio of air density to 1 compared with the density of other gases under the same pressure and temperature conditions is called relative density. The table below shows the relative densities of the various gases. A gas with a relative density of less than 1 indicates that it is heavier than air, and a gas greater than 1 indicates that it is heavier than air.

Table of relative densities of various gases.

The name of the gas is relative density.

Hydrogen, nitrogen, oxygen, carbon dioxide.

Carbon monoxide. Radon gas density - the relationship between airway resistance and air density.

When breathing, the gas passes through the respiratory tract to create a certain resistance (frictional force), and the denser the inhaled gas, the greater the resistance of the respiratory tract. With the increase of pressure, the respiratory resistance and ventilation function of patients who are undergoing ** in the hyperbaric oxygen chamber will increase, resulting in: hypoxia; carbon dioxide retention; Respiratory muscle fatigue.

Although inhaled pure oxygen can compensate for hypoxia, carbon dioxide retention and respiratory muscle fatigue cannot compensate. Therefore, when hyperbaric oxygen is necessary for patients who are frail, emaciated, myopathy, or myasthenia gravis, it is necessary to use low pressure (no more than 2ATA) and shorten the time.

The density of the gas is not fixed, depending on the specific gas.

Gas density refers to the mass of gas per unit volume at a certain temperature and pressure, which is the density of air.

Calculation: The density of a gas is equal to the mass of the gas divided by the volume of the gas. Under standard conditions, the volume of any 1 mole of gas is 22.4 liters, and the mass of 1 mole of gas is equal to its relative molecular mass (the gas cannot be a mixture), so the density of the gas in standard conditions can be estimated from these two data.

A gas is a fluid like a liquid: it can flow, it can be deformed. Unlike liquids, gases have a large distance between their molecules and can be compressed and expanded. If there is no restriction (container or force field), the gas can expand without limiting its volume.

The atoms or molecules of gaseous matter can move freely with each other. The kinetic energy of atoms or molecules of gaseous substances is comparatively high. The form of a gas can be affected by its volume, temperature, and pressure. These elements make up a number of gas laws, and the three can influence each other.

ρ=pm/rt。where is the density, p is the gas pressure, r is the state constant, and t is the absolute temperature.

Gas is one of the four basic states of matter (the other three are solid, liquid, and plasma). Gases can be composed of a single atom (such as a noble gas), an elemental molecule composed of one element (such as oxygen), a compound molecule composed of multiple elements (such as carbon dioxide), etc.

1. Weighing method:

Equipment: balances, graduated cylinders, water, metal blocks, strings.

Steps: 1) Weigh the mass of the metal block with a balance;

2) Inject an appropriate amount of water into the graduated cylinder, and the reading volume is V1, 3), Tie the metal block with a string and put it into the graduated cylinder, immerse it, and the reading volume is V2.

Evaluate the expression: =m (v2-v1).

2. Gravity cup method:

Equipment: beakers, water, metal blocks, balances,

Steps: 1) Fill the beaker with water and put it on the balance to weigh the mass m1;

2) Gently put the block into the water, overflow part of the water, and then put the beaker on the balance to weigh the mass as m2;

3) Take out the metal block, put the beaker on the balance and weigh the mass m3 of the beaker and the remaining water.

Calculation expression: = water (m2-m3) (m1-m3).

3. Archimedes' Law:

Equipment: spring scales, metal blocks, water, strings.

Steps: 1) Tie the metal block with a string, and weigh the gravity g of the metal block with a spring scale;

2) Completely immerse the metal block in water, and weigh the apparent weight g of the metal block in the water with a spring scale;

Calculation expression: =g water (g-g).

Application of density:

1. Scientifically.

1. Identify the materials that make up the object.

Density is one of the properties of matter, each substance has a certain density, and the density of different substances is generally different. Therefore, we can use density to identify substances. The method is to determine the density of the substance to be measured, and compare the measured density with the density of various substances in the density table, so that you can identify what kind of substance the object is made of.

2. Calculate the composition of various substances contained in the object.

3. Calculate the mass of an object that is difficult to weigh or the volume of an object with a complex shape.

According to the variant of the density formula: m=v or v=m, the mass and volume of the object can be calculated, especially for some problems where the mass and volume are inconvenient to measure directly, such as calculating the volume of an irregularly shaped object, the mass of a monument, etc.

Second, agriculture.

It is an important criterion for density. In agriculture, it can be used to judge the fertility of the soil, and the soil with more humus is fertile, and its density is generally kilograms. When we select seeds, we can select seeds according to the sinking and floating conditions of seeds in the water

The plump and robust seeds sink due to their high density; Deflated husks and other weed seeds float on the surface of the water due to their low density.

In industrial production, for example, the production of starch uses potatoes as raw materials, and generally speaking, the density of potatoes with more starch is larger, so the yield of starch can be estimated by measuring the density of potatoes.

Third, industrially.

Before casting the metal, the factory needs to estimate how much metal will be melted, and the amount of metal required can be calculated based on the volume of the mold and the density of the metal.

The identification method of ultra-practical jade - density measurement.

Hey, this one, it's relatively simple to write on straw paper, but it's a bit difficult to express here, I'll try to be as detailed as possible, I hope you can understand! College Formula.

First through this equation:

pv=nrt

p is the standard atmospheric pressure, t is 273k).

The density under the standard condition you will find (i.e. the density at 0 degrees, one standard atmosphere) where v=m a

The density is denoted by a first).

Bring in p(m a)=nrt

Then bring the density a1 you want to calculate, and the pressure p1 temperature t1 at that time into p1(m a1)=nrt1

Comparing the above two equations, we can get the density at any temperature and pressure, a1=a(t t1)(p1 p).

The premise is that you need to find the density in the standard state in the manual, that is, the density at a standard atmospheric pressure of 0 degrees, or calculate it first.

I hope you can understand, if you can't do it, I'll help you explain, I hope it will help you!

Bring your own formula to prevent me from making mistakes.