Ask for answers to a few questions in physics and chemistry

1 The steel sample to be tested contains 9mg mass fraction=

2 Loss: i=p u=200000 120= u=ir=50vSimilarly: u=5v

Input: U=120-50=70V

u=1200-5=119v

loss of p: p=i2r=

p=i2r=

3. A circuit composed of an inductance coil and a capacitor is called an oscillation circuit. In the oscillation circuit, the charge on the capacitor plate, the current in the circuit, the electric field strength of the capacitor, and the magnetic induction intensity of the coil magnetic field change periodically, which is called electromagnetic oscillation. The open circuit in the oscillation circuit emits electromagnetic waves.

The frequency of the electromagnetic wave is the frequency of the electrical oscillating current.

Set the standard steel sample with CXG

c + o2 = co2

xg12:44=

x=9mgmass fraction=

A: ......

I studied physics and have no interest in chemistry, so the physics problem is like this: because i=p u, you can use w=i2r, which is why we use high-voltage power transmission.

This problem requires the calculation of the equilibrium constant of a chemical reaction. 12 The equilibrium constant is expressed as k= [c p · c q (d)] c m (a) · c n (b)], where m, n, p, q are stoichiometric numbers and c is the concentration or partial pressure. 1 You can first write out the reaction equation in the problem, then calculate the equilibrium constant k according to the given g° and t, then substitute the partial pressure to find q (reaction quotient), and finally compare the magnitude of q and k to determine the direction of the reaction.

First, the process is isobaric expansion, and the gas does work on the outside world.

w=-f*x=-pv=101000*

Another 125j of heat was absorbed.

Change u=(125-606)j

So the internal energy is reduced by 481j

Second, there are two ways to the energy of the chemical reaction, one is to give electric energy, and the other is to lose heat, because the electric work is 800J, so the heat is dissipated 1200Jq=-1200J

Simple dissolution process, nothing like chemical equilibrium is involved, several substances are divided into several groups, 1 is 5 for the group, 2 is 3 for the group.

f = group score + number of phases - 2

If the solids are completely dissolved, 1,2 are single-phase. The solid is not completely dissolved, depending on the insoluble substance, for the solid, several substances are several phases.

1) Solid sodium chloride, potassium chloride, sodium nitrate, potassium nitrate mixture and water oscillation direct equilibrium considering the dissociation of four solid substances and the dissociation of water, the dissociation of four solid substances has four chemical equilibrium, according to the standard equilibrium constant, there is an equation between the four equilibrium constants, that is, four solid dissociation equilibrium, three are independent, r = 3 + 1 = sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, water, sodium ion, potassium ion, nitrate, chloride ion, hydrogen ion, hydroxide a total of 11 kinds. r'= 2 (equal concentration of hydrogen ions, hydroxides; Electrically neutral).

c=s-r-r'=11-4-2=5,f=c-p+2=5-5+2=2 p=5 (four solids have four phases, one liquid phase).

2) Solid mixture of sodium chloride, potassium nitrate and water.

There are three equilibrium to consider the dissociation of the three substances.

s=9-3-3=3 f=c-p+2=3-3+2=2

1.False, mixtures can also be molecular and proto-ridge, or even ionic, such as various solutions, which are ionic, molecular or atoms and water.

Compounds, which can also be molecular, wonder how this topic came up, just give a random example of molecules, such as water.

Physics. 1.This upstairs has been said very clearly, and will not be repeated.

2.Alcohol, in addition to the gas used in many places now, is slightly more polluted.

3.This is definitely not, the cylinder is small, the power is insufficient, the family car is literal, literal, larger than the liter is called a large displacement, of course, not a cylinder displacement, they are usually several cylinders, four cylinders, or 6 cylinders.

4.This is a problem of energy conversion, which is converted from the nuclear chemical energy of gasoline (diesel) into air internal energy, and then into the mechanical energy of piston movement.

5. After the combustion of gasoline, the heating air expands to promote the movement of the piston, and the chemical energy is converted into air internal energy, and then converted into mechanical seepage energy to drive the crankshaft to do circular motion through the connecting rod, so as to drive the wheel to rotate, and then the piston will compress the air, and part of the mechanical energy is converted into internal energy, resulting in gasoline**, heating gas, re-expansion, and so on.

Chemistry. 1.False [Example: KCl, NaCl mixed solution is a mixture, but both are ions.

Aluminum alloys are also mixtures, all atoms

Physics. 1.When the Curie temperature is reached or close to that of the steel, the magnetic domains gain energy and flip irregularly. Overall, it is non-magnetic.

2.(1) Liquefied hydrogen (2) Liquefied natural gas.

3.[I don't know too much about the heat engine].

4.The energy obtained from the compression and combustion of the last ruined pants [think of the automatic pistol] 5In the process of compressing gas, the piston does work on the gas, so there is compressed gas. Then the compressed gas deflagrates again, and the pure thought is used to work on the piston.

1) Incorrect. The mixture can be elemental + compound, such as copper shavings + water.

The compound is the jujube.

1. Magnetic materials will be demagnetized after reaching a certain temperature, which is called Curie temperature or Curie point. A common application is the rice cooker, where the magnet loses its magnetism at 105 degrees and loses power, realizing the function of automatic rice cooking.

2. Ethanol, petroleum liquefied gas.

4. Mechanical energy produced by gasoline in a gasoline engine**.

5. Through the piston, the external parts are driven to move and do work.

The master will help you answer:

The main premise is when you don't do non-expansion work:

Step 1: Calculate the amount of gaseous substances n=pv rt;

Isothermal reversible expansion: it belongs to the work done by expansion, t is unchanged, so u=0, w=(nrt)ln(v1 v2), q=u+w can be calculated, h and u are both functions of temperature, so h= u;

Vacuum expansion: vacuum expansion is external pressure p=0, which belongs to the enthalpy process and belongs to free expansion, so w=0, that is, the system does not work externally; △u=q=△h=0；

Adiabatic reversible expansion: q is unchanged, w=u=ncv(t2-t1), for a single-atom ideal gas, cvm=(3 2)r, cpm=(3 2+1)r, so r=5 3 can be calculated; The temperature was calculated with PV=NRT. H and U are both functions of temperature and have nothing to do with p and v, so u = h=w;

Adiabatic constant external pressure expansion: p is unchanged, w=p(v2-v1), so it can be found; Q unchanged! △u=△h=w。