A 50 point reward is urgently needed for junior high school chemistry experiment questions

1. NaOH + CH3COOH = CH3COONA + H2O So when NaOH and CH3COOH react completely, the amount of NaOH and CH3COOH substances consumed is equal.

The volume of NaOH consumed was measured by Experiment 2, and the concentration of NaOH was known and the volume of acetic acid was known, from which the concentration of the CH3COOH solution could be found.

2. Magnesium powder and sodium carbonate must be used to get out the excess acetic acid in the reaction! But I don't know where to use it. But I don't think it's meant to get rid of the ch3cooh that was splashed during the experiment

1. How to determine the concentration of acetic acid?

NaOH + CH3COOH = CH3COONA + H2O So when NAOH reacts completely with CH3COOH, the number of moles of NAOH and CH3COOH consumed is equal.

The volume of NaOH consumed was measured in Experiment 2, and the concentration of the CH3COOH solution can be found using the known concentration of NaOH and the known volume of CH3COOH (2L).

2. Not very clear. Acetic acid is strongly corrosive and may be used to remove ch3COOH from the spilled experiment

mg+2ch3cooh=(ch3coo)2mg+h2na2co3+ch3cooh=nahco3+ch3coona

v1×c1 v2×c2

Experiment 2 The volume of NAOH consumed V1 can be measured, the concentration of NAOH C1 and the volume of acetic acid V2 are known, the dosage of NaOH is V1 C1, the dosage of acetic acid is V2 C2, and the column formula 40 (V1 C1) 60 (V2 C2), so C2 3(V1 C1) 2V2

Upstairs is explained by the amount of matter, as if it is not suitable for junior high school students) 2In the experiment, magnesium powder and sodium carbonate powder need to be added to check whether the acetic acid is completely reacted.

Even a chemistry teacher, no problem.

Do junior high school students have such difficult questions?

Hello, the correct answer is bc

C is a sufficient amount of dilute hydrochloric acid, and the balloon is sodium carbonate powder, so the function of the balloon is to add sodium carbonate to the dilute hydrochloric acid at any time to make the reaction occur and produce carbon dioxide, which is the effect of adding solid drugs.

If you have any questions, please feel free to ask.

Good luck with your learning and progress.

The correct answer is: B, oh, pro, oxygen is produced in A, and the lime water in B is squeezed into C for a reaction, and then the air pressure increases, and the sodium carbonate in the balloon is thrown into C for a reaction.

a. Sodium carbonate can dry the obtained oxygen as water vapor in the gas, so it is to obtain a pure gas.

The answer is B, because the reaction of device A will cause a pressure difference in device C, which will inflate the balloon, and the solid drug will fall into device C and react.

b Add solid medicine c Adjust C Device volume.

b Add solid drugs.

Because A produces oxygen, calcium hydroxide is pressed into C, reacts with hydrochloric acid, and is exothermic, causing the balloon to inflate, and the solid falls into C, adding solid drugs.

BC Sodium carbonate and hydrochloric acid produce CO2 I don't think the topic is complete.

Steps and methods: (1) Before ignition: observe the color, state, shape, smell of the candle, and detect the hardness, density and solubility.

Phenomenon: White columnar solid, difficult to water. Scratching the surface of the candle with your fingernail will leave scratchesWhen a small piece of paraffin is placed in water, the paraffin block is placed on the surface of the water (on or under).

Explanation and conclusion: Paraffin wax is softer (filler "hard", "soft" or softer), difficult to water, and less dense than water

Steps and methods: (2) When igniting: aLight the candle bUse a toothpick to slowly pan through the flame cTake a dry beaker and a beaker that moistens the inner wall with clear lime water, cover the flame one after another, and remove the beaker after a while.

Phenomenon: The candle will continue to burn, slowly decreasing, some of the candles will flow down after melting, and will be solid after cooling. Observe the candle flame, which is divided into three layers: outer flame, inner flame, and flame center.

The toothpick turns black first in the outer flame part (fill first or last), and does not turn black in the flame center part. Water droplets appear on the inner wall of the dry beaker, and the clarified lime water becomes cloudy

Explanation & Conclusion: Candles are flammable. The outer flame temperature is the highest, and the outer flame of the alcohol lamp should be heated when heating, and the candle burns to produce water and carbon dioxide

Steps and methods: (3) After extinguishing: light the white smoke when the candle has just been extinguished.

Phenomenon: A wisp of white smoke wafts out of the center of the flame, igniting the white smoke, and the flame will (or not) rekindle the candle along the white smoke.

Explanation and conclusion: White smoke is a small solid particle formed by paraffin vapor condensation, which is also flammable.

5.Expression and communication (express the above chemical reactions in words): paraffin wax + oxygen - arrow - water + carbon dioxide

6.Brackets & Migrations: Fill in the form yourself

1.White (red) cylindrical solid not soluble in water Hang down candle on Small Not soluble in Small 2

ch4+h2o=co+3h2

From this reaction, we can see that if there is only CO and H2, then the production of a CO molecule corresponds to the production of 3 hydrogen molecules, and then there is a carbon atom in a CO molecule, and the total relative mass of the carbon element is 12; There are 6 hydrogen atoms in 3 hydrogen molecules, and the relative mass of the total hydrogen element is 6*1=12, so the mass ratio of carbon to hydrogen is 2:1

If there is only CH4, then both carbon and hydrogen are from CH4, and it can be seen from the molecule CH4 that one carbon atom corresponds to 4 hydrogen atoms, so the mass ratio of carbon to hydrogen is 12*1:4*1=3:1

Do you just want to know these 2 ratios?

1)ch4+h2o=co+3h2

2)i．14：3

Refine the experimental design] Conduct the experiment] Red.

Phenomenological analysis and data processing].

If only CO and H. Reducing sufficient CuO, the ratio of the number of molecules of CO to H2 in the syngas is 1:3. The mass ratio of carbon to hydrogen in the product is 2; 1

If only CH4 reduces a sufficient amount of CuO, the mass ratio of carbon to hydrogen element in the product is 3:1

The mass of CO2 is measured: 201 5g - 198 2g = 3 3g H20 mass: 896 0g - 292 4g = 3 6g

The mass ratio of carbon element cord to hydrogen element cord in the product is (3·3g)3 6g)9:4

9；4 is between 2:1 and 3:1.

It can be inferred that, in addition to CO and H2, there may be CH4 in the syngas produced to react.

CH4 also restores cuo. (Reasonable process is evenly scored).

Not. Since the removal of water vapor will cause the measured CO2 mass to be low, and the mass ratio of carbon to hydrogen in the actual product is greater than 2:1, it has no effect on the estimated results. (Points are given for reasonable descriptions).

Expand**] clarified lime water hgfi

Experimental reflection] Because the mass ratio of carbon and oxygen in the product is too high to 2:1 according to the measured data, it may be that the ratio of the number of molecules of CO to H2 participating in the reaction in the syngas is greater than 1:3 (or H2 does not fully participate in the reaction

1) b Anhydrous copper sulphate CuSO4

c bacl

d koh2)h2o

3) KSO4 or KCl

Give it a few points).

1) Write in chemical formula: B BaCl2, C Koh, D Cu(OH)2

2) If the colorless neutral liquid is also pure, then the neutral liquid is H2O (fill in the chemical formula) 3) If the colorless neutral liquid is a solution containing only one solute, what are the possible conditions of the solute?

k2SO4, kcl write chemical formula).