Speed v (m/s) v = s/t; S: distance, t: time

Gravity g (n) g = mg; M: quality; G: 9.8n/kg or 10N/kg.

Density ρ(kg/m3) ρ= m/V m: mass; Five: volume

The resultant force f and (n) are in the same direction: f and =F 1+F2.

Opposite direction: f = f1-when F2 is opposite, f1> Second generation

Buoyancy f float (N) F float =G object -g sight; G-vision: gravity of objects in liquid.

Buoyancy f float (N) F float =G object; This formula only applies to floating or suspended objects.

Buoyancy F float (N) F float =G row =m row g=ρ liquid gV row; G row: gravity of displacement liquid; Line M: mass of displaced liquid, ρ liquid: density of liquid, and line V: volume of displaced liquid (i.e. volume immersed in liquid).

The equilibrium condition of lever f1* l 1 = F2 * l2f1:power, l1:power arm F2: resistance L2: resistance arm.

Crown block F=G object, S=h, f: the tension of the free end of the rope, g object: the gravity of the object, s: the distance that the free end of the rope moves, and h: the distance that the object rises.

Moving pulley F= (G object +G wheel) /2, S=2 h, g object: object gravity, g wheel: moving pulley gravity.

Pulley block F= (G object +G wheel) /n, S=n h, n: the number of segments bearing the weight of the object.

Mechanical work W(J) W=FS F: force s: distance moved in the direction of force.

Useful work: w available, total work: w is total, w is =G *h, w is total =Fs, and the mechanical efficiency η=W available /W is total × 100% when the pulley block is placed vertically.

Work W = F S = P t 1J = 1N? m = 1W？ s

Power P = W/t = F*v (uniform straight line) 1kw = 10 3w, 1mw = 10 3kw.

Useful Work W Useful = G h= W Total–W Quantity =ηW Total

Extra work w amount = W total amount–w has = G movement h (ignoring friction between shafts) = f L (inclined plane)

Total workload W Total = W Useful +W Quantity = F S = W Useful/η

Mechanical efficiency η = useful power/total power

η = g/(n f) = g-object/(g-object+g-motion) This definition applies to moving pulleys and pulley blocks.

Power p (w) p = w/t; W: work; T: time

Pressure p(Pa) P= F/S F: pressure /S: stress area.

Liquid pressure p (pa) p = rhogh rho: liquid density h: depth (vertical distance from liquid surface to required point)

Heat Q(J) Q=cm△t c: specific heat capacity m: mass, △t: change value of temperature.

Heat released by fuel combustion q (j) q = MQ; M: mass, q: calorific value.

series circuit

Current I (a) I = I 1 = I2 = ... Current is equal everywhere.

The voltage u (v) u = u 1+U2+ ... The series circuit acts as a voltage divider.

The resistance r (ω) r = r 1+R2+ ...

parallel circuit

Current I (a) I = i 1+I2+ ... The main current is equal to the sum of the currents of each branch (shunt).

Voltage u (v) u = u 1 = U2 = ...

Resistance1/r (ω) =1/r1+1/R2.

Ohm's law I= U/R

The current in the circuit is directly proportional to the voltage and inversely proportional to the resistance.

Current definition formula I= Q/t: charge (coulomb) t: time (second)

Electric work w (j) w = uit = pt; U: voltage I: current t: time p: electric power

Electric power p = ui = I 2r = u 2/r u: voltage I: current r: resistance.

Electromagnetic wave velocity and wave

The relationship between length and frequency c=λf

C: wave velocity (the wave velocity of electromagnetic wave is constant, equal to 3× 10 8m/s) λ: wavelength f: frequency.

2. Knowledge points

1. Several values to remember:

A. The propagation speed of sound in the air: 340m/s;

B the propagation speed of light in vacuum or air: 3x108m/s.

C density of water: 1.0× 10 3kg/m3 d specific heat capacity of water: 4.2× 10 3j/(kg? ℃)

E. dry battery voltage:1.5v f. household circuit voltage: 220V.

G. safe voltage: not higher than 36V.

2. Density, specific heat capacity and calorific value are the characteristics of substances, and the values of these three physical quantities of the same substance are generally unchanged. For example, a glass of water and a bucket of water have the same density and specific heat capacity.

3. A virtual image of the same size formed by a plane mirror, in which the image and the object are symmetrical about the plane mirror.

Sound cannot travel in a vacuum, but light can travel in a vacuum.

4. Ultrasonic waves: sounds with frequencies higher than 20000Hz, such as bats, ultrasonic waves, dolphins, etc.

Infrasound: Infrasound can be produced by volcanic eruption, earthquake, wind explosion and tsunami below 20Hz, nuclear explosion and missile launch.

6. Light travels in a straight line in the same homogeneous medium. Shadow, pinhole imaging, solar eclipse and lunar eclipse are all formed by light propagating along a straight line.

7. When light is refracted, the angle in the air (the angle with the normal) is always slightly larger. When you look at something in the water, you see a shallow virtual image (conversely, the trees on the shore become taller when you look at it in the water).

8. Convex lens converges light and concave lens diverges light.

9. The law of convex lens imaging: the object becomes a reduced and inverted real image (camera) at a distance of twice the focal length. Between the focal length of 2 times and the focal length of 1 times, it becomes an inverted magnified real image (projector). In the focal length range of 1 times, it becomes an upright magnified virtual image (magnifying glass).

10. Sliding friction is related to pressure and surface roughness. Rolling friction is smaller than sliding friction.

1 1. Pressure is a physical quantity that compares the effect of pressure, and the effect of pressure is related to the size of pressure and the stress area.

12. When transmitting electric energy, high voltage power transmission should be adopted. The reason is that the power loss on the transmission line can be reduced under the same transmission power.

13. The principle of the motor: the electrified coil is forced to rotate in the magnetic field. It is the conversion from electric energy to mechanical energy.

14. Generator principle: electromagnetic induction phenomenon. Mechanical energy is converted into electrical energy. Microphones and transformers are based on the principle of electromagnetic induction.

15. Optical fiber is the medium for transmitting light.

16. The magnetic induction line emanates from the N pole of the magnet and finally returns to the S pole.

Chemistry:

Lecture 1: Entering the Chemical World

1, what is chemistry?

2. How to learn chemistry? ① Methods of learning chemistry: experimental exploration; ② The tools for learning chemistry are: periodic table of elements; ③ The characteristics of chemistry learning are: three concerns (focusing on the composition, properties and changing laws of substances).

3 Basic skills of chemical experiment:

(1) to obtain drugs. Powder solid, medicine spoon or paper trough; Block solid, tweezers; A small amount of liquid, dropper; A certain amount of liquid, measuring cylinder or dropper; The amount is not specified in the experiment, and the minimum amount is generally used; Liquid 1-2 ml, and solid covers the bottom of the test tube.

(2) heating of substances. The commonly used heating appliance is alcohol lamp (the wick should be cut flat, the wine should not be put on the shoulder, and the temperature of the inner flame is low. When turning off the light, use a cap, and it is most taboo to blow with your mouth). Heat the solid material (the test tube is fixed with an iron frame, and the iron clip is one-third away from the mouth. The mouth of the heated test tube is inclined downward to avoid cracking of the reflux tube. The solid is laid flat near the bottom of the tube, and the moving flame is heated evenly. After use, cool it and then remove it. Don't worry if it is clean and stable). Heat the liquid substance (the liquid content is less than one third, the outer wall should be dry to prevent burning and cracking, the handle should be supported by a wooden clamp tube, the liquid level and bottom should be heated evenly, and the nozzle should face the air, not the person).

③ Cleaning of instruments (glass instruments). Standard: the water film attached to the inner wall is uniform, and will not agglomerate or flow down in strands. Methods: Use a brush, rinse with detergent and water. Special oil stain: wash with water-insoluble alkali, metal oxide and carbonate, dilute hydrochloric acid, manganese dioxide and potassium permanganate, concentrated hydrochloric acid and hot alkali such as sodium carbonate.

④ Gas collection. Drainage method is suitable for gases that are insoluble in water or insoluble in water and do not react with water. Upward exhaust method is suitable for gases with higher gas density than air. Downward exhaust method is suitable for gases with lower gas density than air.

1, which of the following options do you think does not belong to the scope of chemical research is (c)

A, composition and structure of matter B, changes and properties of matter

C, the motion state of the substance D, the use and preparation of the substance

2, the following belongs to the physical change is (C)

A, rice turns into wine b, kitchen knife rusts c, wet clothes dry d, food goes bad.

3, the remaining drugs in the chemical laboratory, the correct treatment method is (b)

A, take it home; B, pouring into a designated container; C. Pour into the sink at will; D, back to the original reagent bottle.

4, laboratory gas collection method selection, don't have to consider the following properties is (a)

A, color b, density c, solubility d, whether it reacts with water.

5, an experimental report has the following records, of which the experimental data is reasonable (A).

A, weigh 1 1.7g copper oxide powder b with a tray balance, and measure 5.26ml sulfuric acid solution with a 100ml measuring cylinder.

C, the ph value of the solution is 3.5 D measured by pan-ph test paper, and the temperature figure displayed on the thermometer is 25.68℃.

6.NO is a gas at room temperature, hardly soluble in water, slightly denser than air, and can quickly react with oxygen in the air to generate NO2 gas. Now to collect a bottle without gas, the collection method should be (a)

A, only drainage method B, upward ventilation method C, drainage method or upward ventilation method D and downward ventilation method can be used.

7, the following experimental operation, the error is (c)

A, before making carbon dioxide gas, check the air tightness of the device.

Check the purity of chlorine before igniting oxygen.

C. Blow out the flame of the alcohol lamp with your mouth.

D, before burning the iron wire in oxygen, add a small amount of fine sand to the bottom of the gas container.

8, the following glassware cleaning, the correct is (AD)

A, rinse the oil in the test tube with hot soda solution first, and then rinse with clear water.

B, first pour the waste liquid in the test tube into the sewer, and then rinse it with clear water.

C, copper hydroxide, first dissolved with caustic soda solution, and then washed with water.

D, firstly, clean the beaker containing lime water and leaving solid substances with dilute hydrochloric acid, and then clean it with clear water.

9. The following instruments can dissolve solids, prepare solutions and heat various reagents. The three purposes are (b)

A, conical flask b, beaker c, measuring cylinder d and test tube

10. Dropping copper sulfate solution into a test tube filled with sodium hydroxide solution, a blue solid was observed. If the test tube is heated, the observed phenomenon is that the blue solid turns black.

1 1. Through experimental research, the content of exhaled gas has changed obviously compared with inhaled gas, mainly in three substances: oxygen, carbon dioxide and water vapor.

12. Put the beaker forward, cover it with a glass sheet, and collect colorless and nontoxic gas in the beaker. The knowledge learned is used to explore and determine what gas may be.

A: It is known that the specific gravity of this gas is greater than that of air, and it is colorless and nontoxic. From the hypothesis, verification methods, possible phenomena and conclusions to explore. It may be carbon dioxide gas. Pour in clarified lime water for verification. If limewater becomes turbid, then the gas is carbon dioxide. It may also be oxygen, and the wooden strips with mars verify this. If the wood is rekindled, then the gas is oxygen.

13. Burning candles in the air will produce water and carbon dioxide, which will be introduced into a flask with candles and then into clear lime water. The phenomenon seen in the above experiment is that the candle goes out and the clarified lime water becomes turbid. Therefore, the chemical nature of carbon dioxide is that carbon dioxide can neither burn nor support combustion, and carbon dioxide can react with clear limewater.

14. Invert a large test tube filled with sulfur dioxide in the sink, and the water level in the test tube rises above the water level in the sink. What nature can you draw from it?

A: Sulfur dioxide is soluble in water (or can react with water).

(1) Design experiment to prove the acidity and alkalinity of the liquid in the test tube? (block the nozzle with your thumb, remove it from the water surface, drop the purple litmus test solution into the test tube or measure the pH value with pH test paper. )

(2) From this experiment, can you think that the chemical properties of sulfur dioxide are similar to what kind of gas we have learned? Try to write a similar chemical equation. (Carbon dioxide reacts with water or sodium hydroxide, H2O+SO2 = H2SO4)

Unit 3 Understanding Water in Nature

I. Water

1, composition of water:

(1) water electrolysis experiment

A. Device-water electrolyzer

B. Power supply type-DC

Charge

The purpose of adding sulfuric acid or sodium hydroxide is to improve the conductivity of water.

D. chemical reaction: 2h2o = = 2h2 =+O2 =

Generation position negative electrode positive electrode

Floor area ratio 2: 1

Mass ratio 1: 8

F. Inspection: O2—— Put a wooden strip with sparks at the air outlet —— The wooden strip is re-ignited.

H2-the air outlet is equipped with a burning wood-the gas burns to produce a light blue flame.

(2) Conclusion: ① Water is composed of hydrogen and oxygen. ② A water molecule consists of two hydrogen atoms and 1 oxygen atom.

(3) In chemical changes, molecules can be separated, but atoms cannot be separated.

According to the chemical formula H2O of water, what information can you read?

The meaning of chemical formula H2O

(1) said a substance water this substance.

(2) indicates the composition of the substance. Water consists of hydrogen and oxygen.

(3) A molecule representing this substance, a water molecule.

(4) indicates the molecular composition of the substance. A water molecule consists of two hydrogen atoms and one oxygen atom.

Charge

2. Chemical properties of water

(1) charged decomposition 2H2O = = = 2H2 =+O2 =

(2) Water can react with basic oxides to generate alkali (soluble alkali), such as H2O+CaO==Ca(OH)2.

(3) Water can react with acidic oxides to generate acids, such as H2O+CO2==H2CO3.

3. Water pollution:

(1) water resources

A. 7 1% of the earth's surface is covered with water, but less than 1% of fresh water is available for human use.

B.the ocean is the largest reservoir on the earth. Seawater contains more than 80 elements. The most abundant substance in seawater is H2O, the most metal element is sodium, and the most element is oxygen. ..

C. The distribution of water resources in China is uneven, and the per capita possession is small.

(2) Water pollution

A water pollutants: industrial "three wastes" (waste residue, waste liquid and waste gas); Unreasonable use of pesticides and fertilizers

Discharging domestic sewage at will

B, prevent water pollution: industrial waste should be treated and discharged up to standard, and zero discharge should be advocated; Domestic sewage should be treated centrally to meet emission standards and advocate zero discharge; Rational use of pesticides and fertilizers, advocate the use of farmyard manure; Strengthen water quality monitoring.

(3) Care for water resources: save water and prevent water pollution.

4. Purification of water

(1) The purification effect of water from low to high is standing, adsorption, filtration and distillation (all physical methods), among which distillation operation has the best effect; The water purifying agent with filtration and adsorption functions is activated carbon.

(2) Hard water and soft water A. Definition Hard water is water containing more soluble calcium and magnesium compounds;

Soft water is water containing no or little soluble calcium and magnesium compounds.

B identification method: soapy water, hard water with scum or less foam, and soft water with more foam.

C. methods of softening hard water: distillation and boiling.

D. Disadvantages of long-term use of hard water: waste of soap and inability to clean clothes; Boilers are easy to scale, which not only wastes fuel, but also easily deforms pipelines and even causes boiler explosion.

5. Others

(1) water is the most common solvent and the oxide with the smallest relative molecular weight.

(2) Water inspection: anhydrous copper sulfate, if it changes from white to blue, indicates the existence of water; Copper sulfate +5H2O = copper sulfate 5h2o

Water absorption: concentrated sulfuric acid and quicklime are commonly used.

Second, hydrogen H2

1, physical property: the gas with the lowest density (downward exhaust method); Insoluble in water (drainage method)

2, chemical properties:

(1) ignition

Combustibility (use: high-energy fuel; Hydrogen and oxygen flame welding, cutting metal)

2H2+O2 = = = 2H2O Before ignition, measure the purity (method? )

Phenomenon: emit light blue flame, release heat and produce water droplets.

(2) △

Reducibility (use: smelting metal)

H2+CuO = = Cu+H2O Hydrogen "Go out early and return late"

Phenomenon: black powder turns red, and water droplets form at the mouth of the test tube.

(Summary: combustible and reducing substances H2, carbon and carbon monoxide)

3. Laboratory method of hydrogen.

Principle: Zn+H2SO4 = ZnSO4+H2 ↑ Zn+2hcl = ZnCl2+H2 ↑.

The reason why concentrated hydrochloric acid cannot be used is that concentrated hydrochloric acid is highly volatile;

The reason why concentrated sulfuric acid or nitric acid cannot be used is that concentrated sulfuric acid and nitric acid have strong oxidizing properties.

4. Hydrogen energy has three advantages: no pollution, high heat release and wide sources.

Unit 2 "The air around us"

1, the first chemist to explore the composition of air: lavoisier (the first one to make quantitative analysis with a balance).

2. Composition and composition of air

atmospheric composition

oxygen

N2

carbon dioxide

rare gas

Other gases and impurities

Volume fraction

2 1%

78%

0.03%

0.94%

0.03%

(1) determination of oxygen content in air

Flammability requirements: sufficient solid products.

Equipment requirements: good air tightness.

C. Phenomenon: a large amount of white smoke is produced, and the liquid level in the tank rises by about 1/5 volume.

D. conclusion: air is a mixture; O2 accounts for about 1/5, which can support combustion;

N2 accounts for about 4/5, which does not support combustion, nor can it burn, and is insoluble in water.

E. inquiry: ① liquid level rise is less than 1/5. Cause: Air leakage, insufficient red phosphorus and incomplete cooling.

② Can iron and aluminum be used instead of red phosphorus? There is no reason: iron and aluminum can't burn in air.

Can carbon and sulfur replace red phosphorus? No reason: the product is gas, and it can't produce pressure difference.

(2) Air pollution and prevention: The main pollutants that pollute the air are harmful gases (CO, SO2, nitrogen oxides) and smoke.

At present, the items included in the air pollution index include CO, SO2, NO2, O3 and inhalable particles.

(3) Harm and protection of air pollution:

Hazards: seriously damaging human health, affecting crop growth, destroying ecological balance, global warming, ozone layer destruction, acid rain, etc.

Protection: strengthen air quality monitoring, improve environmental conditions, use clean energy, and plant trees, trees and grass actively after the waste gas from the factory is treated.

(4) Current environmental pollution problems:

Ozone layer destruction (Freon, nitrogen oxides, etc. ) and greenhouse effect (carbon dioxide, methane, etc. )

Acid rain (NO2, SO2, etc. ) and white pollution (plastic waste, etc. )

6. Oxygen

(1) Chemical properties of oxygen: unique properties: supporting combustion and supplying breathing.

(2) the reaction of oxygen with the following substances

material

phenomenon

carbon

Maintain red heat in the air, emit white light in oxygen, and generate gas to make clear lime water turbid.

phosphorus (P)

Produce a lot of white smoke

sulphur

It emits a faint light blue flame in the air and a bright blue-purple flame in oxygen.

Produce a gas with a pungent smell.

magnesium

Emit dazzling white light, release heat, and generate white solids.

aluminium (Al)

iron

Burning violently, sparks are everywhere, and black solid (Fe3O4) is generated.

paraffin

When it burns in oxygen, it emits white light, and water droplets are generated on the bottle wall, resulting in gas that makes clear lime water turbid.

* When burning iron and aluminum, put a small amount of water or fine sand at the bottom of the gas container to prevent the overflowing high-temperature melt from cracking the bottom of the bottle.

* Iron and aluminum are nonflammable in air.

(3) Preparation of oxygen:

Industrial oxygen production-method of separating liquid air (principle: different physical changes of boiling points of nitrogen and oxygen)

Principle of oxygen production in laboratory: 2h2o 2mno22h2o+O2 =

2k MnO 4△k2mno 4+MnO 2+O2↓

2KClO3MnO22KCl+3O2↑

(4) Selection of gas taking and gathering devices△

Generating devices: solid-solid heating type and solid-liquid unheated type collecting devices: according to the density and solubility of substances,

(5) Operation steps and matters needing attention in oxygen production (taking potassium permanganate oxygen production and drainage collection as an example)

Steps: connect-check-load-fix point-receive-move-extinguish.

Listen

① The mouth of the test tube is slightly inclined downward: to prevent the test tube from being broken due to the backflow of condensed water.

② Spread the medicine on the bottom of the test tube: heat it evenly.

③ The distance between the iron clip and the nozzle is about 1/3.

④ The catheter should be slightly exposed from the rubber plug: it is convenient for gas discharge.

⑤ Put a ball of cotton at the mouth of the test tube to prevent potassium permanganate powder from entering the catheter.

⑥ When collecting by drainage method, collect when bubbles emerge uniformly and continuously (air in the test tube is discharged first).

⑦ At the end of the experiment, move the catheter first, and then put out the alcohol lamp: to prevent the test tube from breaking when pouring water.

When collecting gas by exhausting air, the duct extends to the bottom of the gas container.

(6) Oxygenation: put a piece of wood with Mars at the mouth of the gas container.

Inspection: Stick the wooden strips with sparks in the gas container.

7. Catalyst: A substance that can change the chemical reaction rate of other substances in a chemical reaction, but its own quality and chemical properties have not changed before and after the reaction. (One change and two unchanged)

The role of catalysts in chemical reactions is called catalysis.

8, the use of commonly used gas:

① Oxygen: used for breathing (such as diving and medical emergency).

Support combustion (such as fuel combustion, steelmaking, gas welding)

② Nitrogen: inert protective gas (chemically inert), important raw materials (nitric acid, fertilizer) and liquid nitrogen freezing.

(3) Rare gases (helium, neon, argon, krypton, xenon, etc.):

Protective gas, electric light source (which emits different colors when electrified) and laser technology.

9, common gas inspection methods

(1) oxygen: wooden strips with Mars.

② Carbon dioxide: clarified limewater.

③ Hydrogen: ignite the gas and cover it with a dry and cold beaker above the flame;

Alternatively, hot copper oxide is passed first and then anhydrous copper sulfate is passed.

9. Oxidation reaction: the reaction between a substance and oxygen (oxygen element).

Violent oxidation: combustion

Slow oxidation: rust, human breath, food decay, wine making.