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All formulas of physical acceleration and the solution of proportional method
①V=Vo+at
②x=Vot+2at²
③V²-Vo²=2ax
④Δs=aT²
⑤F=ma
⑥ Centripetal acceleration a = V & sup 2; r = ω & sup 2; r = V ω
X=（v-v0）t/2
t=（v-v0）/a
t=2x/v0+v1
I didn't get it.
What is a?
What is x?
The uniform acceleration linear motion formula, V0 is the initial velocity, V is the final velocity, a is the acceleration,
X is the calculated acceleration a
What is the meaning of this physical formula
Masters, what is the meaning of this physical formula r = u ^ 2 / P = 110 ^ 2 / 60 = 1210 / 6 u ^ 2 / P? What is the meaning of u squared divided by 2 or u squared divided by power? What is the meaning?
It's the square of u divided by power
Because in pure resistance, U / r = I
i*u=p
So u * U / r = P
u*u/p=r
The significance of physical formula
Square of VT - square of VO = 2As
What is the meaning of this formula?
You think, if "the square of the velocity at t minus the square of the initial velocity equals twice the acceleration times the distance", isn't that strange
OK, let's move 1 / 2 and multiply it by a mass m to make 1 / 2mvt ^ 2-1 / 2mv0 ^ 2 = MAS, MAS = f (resultant force) s = work done by resultant force
This is the kinetic energy theorem. Is it strange that the work done by the combined external force is equal to the change of kinetic energy
The method formula of making gas in Chemistry Laboratory of senior high school
1. Preparation and inspection of common gases
(1) oxygen
Principle of preparation -- self decomposition of oxygenated compounds
Preparation equation 2kclo3 2KCL + 3O2 ↑
Device - a large tube tilted slightly downward, heated
Inspection - with spark sticks, reburning
Collection drainage method or upward exhaust method
(2) hydrogen
Principle of preparation -- replacement of active metal with weak oxidizing acid
Preparation equation Zn + H2SO4 = = = H2SO4 + H2 ↑
Device -- Qipu generator
Inspection - ignition, light blue flame, water droplets on the vessel wall
Collection drainage method or downward exhaust method
(3) chlorine
Principle of preparation -- oxidation of oxygenated compounds with strong oxidant
Preparation equation -- MnO2 + 4hcl (concentrated) MnCl2 + Cl2 ↑ + 2H2O
Device: separating funnel, round bottom flask, heating
Test: it can make the wet blue litmus test paper turn red first and then fade;
Impurity removal: saturated salt water (HCl removal) is introduced first, and then concentrated H2SO4 (steam removal) is introduced
Collecting and discharging saturated salt water or exhausting upward
Tail gas recovery -- Cl2 + 2naoh = = NaCl + NaClO + H2O
(4) hydrogen sulfide
① Principle of preparation -- double decomposition reaction of strong acid and strong base
② Preparation equation -- FES + 2HCl = = FeCl2 + H2S ↑
③ Device -- Qipu generator
④ Test - can make wet lead acetate test paper black
⑤ Impurity removal: saturated NaHS solution (HCl removal) is introduced first, and then solid CaCl2 (or P2O5) is introduced (water vapor removal)
⑥ Collection upward exhaust method
⑦ Tail gas recovery - H2S + 2naoh = = Na2S + H2O or H2S + NaOH = = NaHS + H2O
(5) sulfur dioxide
① Principle of preparation -- double decomposition of stable strong acid and unstable weak acid salt
② Preparation equation Na2SO3 + H2SO4 = = Na2SO4 + SO2 ↑ + H2O
③ Device: separating funnel, round bottom flask
④ Test: first pass in the fuchsin test solution, fade, and then heat to restore the original red;
⑤ Impurity removal: introduce concentrated H2SO4 (steam removal)
⑥ Collection upward exhaust method
⑦ Tail gas recovery SO2 + 2naoh = = Na2SO3 + H2O
(6) carbon dioxide
① Principle of preparation -- double decomposition of stable strong acid and unstable weak acid salt
② Preparation equation -- CaCO3 + 2hclcacl2 + CO2 ↑ + H2O
③ Device -- Qipu generator
④ Test: clear lime water is added to make it turbid
⑤ Impurity removal: saturated NaHCO3 solution (HCl removal) and concentrated H2SO4 (water vapor removal) are introduced
⑥ Collection drainage method or upward exhaust method
(7) ammonia
① Principle of preparation -- double decomposition of solid ammonium salt and solid strong base
② Preparation equation Ca (OH) 2 + 2nh4clcal2 + NH3 ↑ + 2H2O
③ Device - a large tube tilted slightly downward, heated
④ Test - wet red litmus test paper, turn blue
⑤ Impurity removal - alkali lime (steam removal)
Collection downward exhaust method
(8) hydrogen chloride
① Principle of preparation -- double decomposition of high boiling point acid and metal chloride
② Preparation equation NaCl + h2so4na2so4 + 2HCl ↑
③ Device: separating funnel, round bottom flask, heating
④ Test: introduce AgNO3 solution to produce white precipitate, then add dilute HNO3 to precipitate insoluble
⑤ Remove impurities - pass concentrated sulfuric acid (remove water vapor)
⑥ Collection upward exhaust method
(9) nitrogen dioxide
① The principle of preparation is oxidation-reduction of inert metals and concentrated nitric acid;
② Preparation equation Cu + 4hno3 = = Cu (NO3) 2 + 2no2 ↑ + 2H2O
③ Device: separating funnel, round bottom flask (or large test tube, conical flask)
④ Test - reddish brown gas, with AgNO3 solution, the color becomes lighter, but no precipitation is formed
⑤ Collection upward exhaust method
⑥ Tail gas treatment -- 3no2 + H2O = = 2hno3 + no
NO+NO2+2NaOH===2NaNO2+H2O
⑩ Nitric oxide
① The principle of preparation is oxidation-reduction of inert metals and dilute nitric acid;
② Preparation equation Cu + 8hno3 (dilute) = = = 3cu (NO3) 2 + 2No ↑ + 4H2O
③ Device: separating funnel, round bottom flask (or large test tube, conical flask)
④ Test - colorless gas, immediately reddish brown when exposed to air
⑤ Collection drainage method
(11) carbon monoxide
① Dehydration of organic matter by concentrated sulfuric acid
② Making equation hcoohco ↑ + H2O
③ Device: separating funnel, round bottom flask
④ Inspection - combustion, blue flame, no water droplets, gas can make clear lime water turbid
⑤ Remove impurities - pass concentrated sulfuric acid (remove water vapor)
⑥ Collection drainage method
(12) methane
① Preparation equation CH3COONa + NaOH CH4 ↑ + Na2CO3
② Device - a large tube tilted slightly downward, heated
③ Collection drainage method or downward air drainage method
Ethylene
① Dehydration of organic matter by concentrated sulfuric acid
② Preparation equation CH3CH2OH CH2 = CH2 ↑ + H2O
③ Device: separating funnel, round bottom flask, heating
④ Impurity removal: NaOH solution (SO2 and CO2 removal) and concentrated sulfuric acid (steam removal) are introduced
Collection drainage method
(14) acetylene
① Principle of making calcium carbide strong water absorption
② Making equation CaC2 + 2h2oca (OH) 2 + CH
③ Device: separating funnel, round bottom flask (or large test tube, conical flask)
④ Test - colorless gas, can burn, produce bright flame, and emit thick black smoke
⑤ Impurity removal: pass in copper sulfate solution (except H2S and PH3) and concentrated sulfuric acid (except water vapor)
Collection drainage method or downward exhaust method
2. Some rapid methods (i.e. without heating) (hand printing)
1. O2 2h2o2 = catalyst MnO2 = = 2H2O + O2
2Na2O2 + 2H2O = 4Na+ + 4OH- +O2
2. Cl2 KMnO4 and concentrated hydrochloric acid
16HCl+2KMnO4=2KCl+2MnCl2+8H2O+5Cl2
3. HCl add concentrated sulfuric acid into concentrated HCl drop by drop
4. Adding Cao or Ca (OH) 2 or NaOH (both solid) into concentrated ammonia water and adding Cao is to use it to react with water to consume water and exothermic. Adding Ca (OH) 2 or NaOH to use it to react with water to exothermic
5.H2 NaH+H20→NaOH+H2↑(
What are the substances that can be identified by the method of mutual dripping in high school chemistry? In detail, it's better to have an equation
It's better to have a phenomenon
When NaOH and AlCl3 were added into AlCl3, white Al (OH) 3 precipitated first and then disappeared to form Na [al (OH) 4] solution; when AlCl3 was added into NaOH, white Al (OH) 3 precipitated
2. For HCl and NaAlO2, when HCl is added into NaAlO2, white Al (OH) 3 precipitates first and then disappears to form AlCl3 solution; when NaAlO2 is added into HCl, white precipitates will not appear or disappear immediately
3. Combination of AgNO3 and NH3 water: there is no obvious phenomenon when AgNO3 is dropped into ammonia water, because the complex is formed. Adding ammonia water into AgNO3 is the phenomenon in silver mirror reaction, and the existing precipitation disappears after excess;
4. Combination of NaOH and AlCl3: when NaOH is added to AlCl3 gradually, precipitation occurs first and then disappears after excess; if the order is reversed, precipitation occurs and then oscillation disappears;
Combination of H2O2 and FeCl3: when hydrogen peroxide is added to the solution containing Fe3 +, only a small amount of gas (oxygen) will be produced instantaneously, but if it is reversed, a large amount of gas will be produced, because Fe3 + added to hydrogen peroxide can catalyze the rapid decomposition of hydrogen peroxide;
5. Combination of HCl and NaAlO2: when HCl is added to NaAlO2 solution, white Al (OH) 3 precipitates first, and then the precipitates are dissolved by excessive HCl. When NaAlO2 solution is added to HCl, precipitation occurs, and the slight oscillation disappears immediately
6. Febr reacts with Cl2, Febr + and a small amount of chlorine to form iron ion, and then bromine ion reacts with bromine ion to form bromine
The equation should be able to write
All the formulas of physics in junior high school
Junior high school physics formula gravity g = mg m: mass G: 9.8n/kg or 10N / kg density ρ = m / V M: mass V: Volume resultant force F = same direction: F = F1 + F2 opposite direction: F = F1-F2 (F1 > F2) buoyancy: F floating = g matter-g
Please pay attention to typesetting and printing
Constant: g = 10N / kg, the speed of light is 3.0 × 108 M / s in vacuum, the speed of sound is 340 m / s in air, the melting point of ice (freezing point of water) is 0 ℃, the boiling point of water is 100 ℃, the density of water is 1.0 × 103 kg / m3, the specific heat capacity of water
Is there a formula for calculating the velocity at the point of displacement? How is it obtained?
v1^-v0^2=ax
v2^-v1^2=ax
v1^2=(v2^2+v0^2)/2
If the acceleration is a, it is proved that S4-S1 = s5-s2 = s6-s3 =. SN-S (n-1) = 3at2
(write down the specific process)
s1=v1t+(1/2)at^2,
s2=v2t+(1/2)at^2=(v1+at)t+(1/2)at^2=v1t+at^2+(1/2)at^2,
s3=v3t+(1/2)at^2=(v2+at)t+(1/2)at^2=v2t+at^2+(1/2)at^2,
So s3-s2 = s2-s1 = at ^ 2
That's the way to prove it. I believe you can prove it yourself
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