A few physical chemistry questions for junior high school, junior high school chemistry and a physic

The smallest atom in mass is the hydrogen atom.

It's like an upside-down enlargement.

Voltaic batteries are the conversion of chemical energy into electrical energy.

Solubility is a physical parameter that does not change at the same temperature.

1。Electron. 2。Amplify what you're right.

3。Maybe 2 and 4

4。Chemical.

5。The title has been done, and it remains the same.

1.The least mass in an atom is --- electron.

2. The solubility of sucrose solids added to the unsaturated solution of sucrose becomes larger.

Because the solubility of any solution is maximum when it reaches saturation.

Sorry for the other questions, I don't understand your question.

1。Electron 2 magnifies the inverted real image The three elements of force: direction, size, and point of action Magdeburg hemispheric experiments proved that there is pressure in the atmosphere Cao Chong weighed that the principle of the elephant is buoyancy = gravity when floating, and the internal pressure of the liquid is similar to that of the atmosphere The voltaic pile is converted into electrical energy, which should be the liquid in the voltaic pile, and our teacher seems to tell us that it is a stack of zinc and copper sheets sandwiched with salt water-soaked paper to form a stack, which produces an electric current, and as long as the temperature is constant, his solubility will also remain the same.

1.The least mass in an atom is --- electron.

2.The object distance is less than the image distance, and the image is an inverted magnified real image, and the one that chooses a to magnify is correct.

3.“1。The Three Elements of Research Force2. Madebao Hemispheric Experiment 3. Cao Chong called Xiang 4. The internal pressure of the liquid is studied.

2 out of 1 I choose 1 and 2 "I'm sorry, I didn't understand this question......But I have a little bit, so I saw a few questions, is it "in some of the following experiments or allusions: The Three Elements of Research Force Magdeburg Hemispheric Experiment Cao Chong Weighs the Elephant To study the law of pressure inside liquids, the scientific thinking method used is the same as ( ) A and B and C and D and "If this is the problem, then D should be chosen for this question (I myself think that D is chosen, and the answer on the Internet is also D......）

4.A voltaic stack is a battery that converts chemical energy into electrical energy.

5.Solid solubility is a property of the substance, independent of the mass of the object, and the solubility of sucrose does not change much with temperature, so this title does not change.

1.Because the magnesium in the right disc will produce hydrogen with sulfuric acid, the mass of the right disc decreases, while the mass of the left disc remains the same, so the right side of the balance is cocked.

Float = 1000x2 1000

x1020 Ox.

w=(60-20)x2=80j

The force area of the cylinder is r 2, r=45mm=. The work done by gas is equal to the pressure (pressure multiplied by area) multiplied by the distance at which the force acts (100mm=:).

The Type 490 diesel is a four-stroke engine (intake, compression, work, exhaust), so it takes two revolutions to complete a power stroke. The power is 4*. If I'm mistaken, it's a two-stroke, and it's doubled.

I'm using the calculator directly, not omitting it.

"light" i.e. (volatile), "irritable" i.e. (flammable and explosive).

1.Let a meal of gasoline provide a calorie of q, and the amount of methanol gasoline sought is x tons. So (here, the heat produced by the complete combustion of each kilogram of methanol is only half that of gasoline, so the heat provided by methanol in methanol gasoline is. Solution x = tons.

2.Tons of gasoline can be saved.

Yuan. 20-16,4g is the mass of the oxygen element taken away by hydrogen, that is, 4 16 = o, that is, cuo, the mass is 20g, and the mass fraction is 100%.

2kmNO4== K2MNO4+MNO2+O2 , so, the reduced mass is oxygen, yes, so the potassium permanganate in the original sample is, yes, the purity is.

New fuel for cars: methanol, gasoline.

Methanol gasoline is very similar to gasoline, the heat generated by the complete combustion of each kilogram of methanol is only half of that of gasoline, but methanol is not as light and "irritable" as gasoline, and "light" is ( ) irritable "that is, it can withstand higher compression in the engine cylinder, that is, in the compression stroke, it can be converted into ( ) energy more, and when doing work, there is more () energy into ( ) energy, which can improve the ( ) of the engine

Therefore, as long as methanol and gasoline are properly matched, they can complement each other's strengths, and studies have shown that gasoline blended with 10 to 25 percent methanol does not require the modification of the car engine to use this fuel blend.

1.If the use of methanol gasoline can increase the efficiency of the automobile engine from the original 30% by 2%, and the original consumption of 1t gasoline, the useful work done by the engine is equivalent to how many tons of methanol gasoline are consumed? (Let the mass ratio of methanol to gasoline be 1:4).

2.How much gas can be saved?

3.If the ** of gasoline is a yuan t, and the ** of methanol is 1 10 of gasoline, how much money can be saved?

37.（2）ba（oh）2

3) K2CO3, hydrochloric acid.

and H2SO4

Because at the beginning of the addition, there is no precipitation to produce H2SO4, but then there is a precipitation, indicating that it is time to start Ba(OH)2 is neutralized with hydrochloric acid, with the presence of acid, there can be no NaOH, and after the hydrochloric acid is neutralized, Ba(OH)2 will continue to react with MgCl2 to produce Mg(OH)2 precipitation.

39.A is Fe, B is Cu, C is Cuo, A is CuSo4, B is FeSo4, and C is H2SO4.

cucl2 b:kcl c:agcl d:cu(oh)2

41.There must be Na2CO3 and K2SO4 and there must be no CuSO4 and Ca(OH)2

bacl2 + na2so4 → baso4↓+2nacl

na2co3 + bacl2 → baco3↓ +2nacl

baco3+ hno3 → ba(no3)2 + h2o + co2↑

If you have any questions, please hi me.

37(2)koh

3) K2CO3, hydrochloric acid.

38naoh

As can be seen from the image, there is a precipitate at the end, indicating that there is MgCl2, but there is no precipitate at the beginning, indicating that NaOH and acid reaction (HCl or H2SO4) are at the beginning, since there is acid, there must be no NaOH

39Fe, Cuo, Cuo, CuSO4, FeSO4, H2SO440CuCl2, KCl, AGCL, Cu(OH)241(3) must have Na2CO3 and K2SO4, and must not have CuSO4 and Ca(OH)2

Equation: BACl2 + Na2CO3 == 2NaCl + BaCO3

bacl2 + k2so4 == 2kcl + baso4↓

;k2co3;hcl

No precipitation at the beginning means that the solution contains HCl, no H2SO4, otherwise it will precipitate at the beginning, and NaOH will be neutralized with hydrochloric acid.

39.Iron, copper, copper oxide, copper sulfate, ferrous sulfate, sulfuric acid 40Copper chloride Potassium chloride Silver chloride Copper hydroxide.

41。There must be sodium carbonate and potassium sulfate, and there must be no copper sulfate and calcium hydroxide.

Na2CO3 + BaCl2 = BaCO3 (precipitate) + 2NaClK2SO4 + BaCl2 = BaSO4 (precipitate) + 2KClBaCO3 + 2Hno3 = Ba(NO3) 2 + H2O + CO2 (gas).

Hello. There are so many questions, let's answer them for the sake of score:

37。 ba（oh)2 k2co3 hcl38.Because there is no precipitation at the beginning, there is no sulfuric acid, there is hydrochloric acid, and later there is precipitation, so there is magnesium chloride so there is no sodium hydroxide.

39.A: FE B: CU C: CUOA: CUSO4 B: FeSO4 C: H2SO4KCl AGCL Cu(OH)2

41.There is Na2CO3 K2SO4 and no CuSO4 and Ca(OH)2

BaCl2 + Na2CO3 = BaCO3 (precipitate) + 2NaClBaCl2 + Na2SO4 = Baso4 (precipitate) + 2NaCl

37.(2) Excessive Ba(OH)2 is added, and the two precipitates produced are magnesium hydroxide and barium sulfate, respectively.

3) Add a slightly excess of K2CO3 to remove the excess of Ba(OH)2, and then add a slightly excess HCl to remove the excess K2CO3.

38.It is impossible to have NaOH and H2SO4, because at the beginning of the addition, there is no precipitation to produce H2SO4, but then there is a precipitation, indicating that it is time to start Ba(Oh)2 is neutralized with hydrochloric acid, with the presence of acid, there can be no NaOH, and after the hydrochloric acid is neutralized, Ba(OH)2 will continue to react with MgCl2 to produce Mg(OH)2 precipitation.

39. Solid A is iron, solid B is copper, solid C is copper oxide, solution A is CuSO4, solution B is Feso4, and solution C is H2SO4.

40、a:cucl2 b:kcl c:agcl d:cu(oh)2 e:cu

41. There must be Na2CO3, K2SO4, there must be no CuSO4, Ca(OH)2 equation is.

na2co3 + bacl2 → baco3↓ +2nacl, bacl2 + na2so4 → baso4↓+2nacl

baco3↓ +hno3 → ba(no3)2 + h2o + co2↑

37 Solution: Ba2+ binds to SO42- to form BaSO4 precipitate.

Mg+ binds to OH- to generate Mg(OH)2 precipitates.

Cl- binds to Ag+ to generate AgCl precipitates.

2) Combined with the topic, only ba(oh)2 conforms to the topic and produces two kinds of precipitation; So what is added is a Ba(OH)2 solution.

3) The filtered solution contains Ba2+, Oh-, Cl-, K+ ions. Excess solution is then added to the filtered filtrate until no bubbles are produced, indicating the introduction of CO3(2-). It was learned that K2CO3 was introduced in the first step, and Ba2+ was removed.

In the second step, hydrochloric acid is introduced, and CO3(2-) and OH- are removed. Reheat before removing HCl.

So an excess of K2CO3 solution and an excess of hydrochloric acid.

38 From the figure, it can be seen that there is no precipitation at the beginning, indicating that there is acid in the solution, and then analyze the figure. So there must be. It can't exist.

39 From the question, it can be seen that solution C must be an acid, and solid C must be an oxide, so the introduction of solid C is Cuo. A: FE B: CU A: CUSO4 B: FeSO4 C: H2SO4

40 analysis flow chart shows that the white precipitate c is agcl, indicating that the filtrate b contains cl-, from the blue precipitate d to the right is Cu(OH)2, after adding dilute sulfuric acid to become a blue solution E is CuSO4, after adding the iron nail, there is a red substance on the surface of the iron nail F is Cu, in summary, a is CuCl2

41 Analysis: (1) dissolving solids in water to obtain a colorless solution; Launching the pack solid must not cuso4

2) Drop into the barium chloride solution in the resulting solution to produce a white precipitate, and the solid of the package must have Na2CO3 and possibly K2SO4

3) A sufficient amount of dilute nitric acid is added to the filtered precipitate, and the precipitate is partially dissolved and bubbles are generated. It means that there must be Na2CO3, K2SO4. In summary, the package must contain Na2CO3, K2SO4, there must be no CuSO4, and there may be Ca(OH)2

bacl2 + na2so4 → baso4↓+2nacl

na2co3 + bacl2 → baco3↓ +2nacl

baco3+ hno3 → ba(no3)2 + h2o + co2↑

It's really lazy, I don't do my homework, I don't even bother to type it on the Internet, and I even take a photo to pass it on**. What kind of homework do you do with this attitude, just drop out of school and go home.

Kids, these questions are not very difficult, so what will you do when you reach high school!