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Papessa [141]
2 years ago
8

Select the correct answer. A student places a sample of white sodium bicarbonate powder in a test tube and heats it. The student

observes that the sodium bicarbonate undergoes a chemical change. After the change, what must be true about the substance in the test tube? A. It is not white. B. It is a liquid. C. It is an element. D. It is not sodium bicarbonate.
Chemistry
1 answer:
inessss [21]2 years ago
8 0

Answer is: D. It is not sodium bicarbonate.

Balanced chemical reaction of heating sodium bicarbonate:                    2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O.

This is chemical change (chemical reaction), because new substances are formed (sodium carbonate, carbon(IV) oxide and water), the atoms are rearranged, so there is no sodium bicarbonate (NaHCO₃) in the test tube.

You might be interested in
Steam initially at 0.3 MPa, 2500 C is cooled at constant volume. (a) At what temperature will steam become saturated vapour? [12
Scilla [17]

Answer:

a. 123.9°C

b.

c.

Explanation:

Hello, I'm attaching a picture with the numerical development of this exercise.

a. Since the steam is overheated vapour, the specific volume is gotten from the corresponding table. Then, as it became a saturated vapour, we look for the interval in which the same volume of state 1 is, then we interpolate and get the temperature.

b. Now, at 80°C, since it is about a rigid tank (constant volume for every thermodynamic process), the specific volume of the mixture is 0.79645 m^3/kg as well, so the specific volume for the liquid and the vapour are taken into account to get the quality of 0.234.

c. Now,since this is an isocoric process, the heat transfer per kg of steam is computed as the difference in the internal energy, considering the initial condition (showed in a. part) and the final one computed here.

** The thermodynamic data were obtained from Cengel's thermodynamics book 7th edition.

Best regards.

7 0
2 years ago
Your friend says, “chemical changes are caused by an input in energy. In physical changes, there is no transfer of energy” is yo
Viktor [21]

Answer: Your friend is incorrect.

Explanation: If we have an object or something that isn’t moving, (let’s say a notebook on a desk). If there is change, and the notebook moves, there is acceleration. Force = Mass times acceleration, f = m*a. There has to be a force, first of all. If you touched the notebook and moved it, some of your energy is transferred and now the notebook has kinetic energy. If our system is you and the notebook, the total energy doesn’t change. the energy is transferred, but doesn’t change. Your friend is not correct. Please give brainliest hope this helped!

6 0
1 year ago
Please Help Me!!
Cerrena [4.2K]

Answer:

1. Galvanic oxidation. Example is the corrosion of aluminium wires when in contact with copper wires under wet conditions.

2. Rainwater or Damp/moist air

3. Chromium-plated steel screws or stainless steel screws or galvanized steel screws

Explanation:

1. Galvanic oxidation or corrosion occurs when two different metals with different electrode potentials are brought into contact with each other by means of an electrolyte (usually a aqueous solution), such that a redox reaction occurs leading to one metal with the more negative electrode potential (the anode) becoming oxidized, while the other less negative potential (the cathode) is reduced.

In order for galvanic corrosion to occur, three elements are required.

i. Two metals with different corrosion potentials (anode and cathode)

ii. Direct metal-to-metal electrical contact

iii. A conductive electrolyte solution (e.g. water) must connect the two metals on a regular basis.

For example oxidation (corrosion) of aluminium wires when in contact with copper wire under wet conditions.

2. The most likely electrolyte will be rainwater containing dissoved solutes (if the panel is in an exposed part of the house) or damp/moist air.

3. From the table, the most likely screw will be chromium-plated steel screws or stainless steel (made of iron and nickel) screws or galvanized steel (zinc-plated) screws.

All these possible screw components have a more negative electrode potential than copper. Thus they will serve as the anode in a galvanic oxidation with copper.

3 0
1 year ago
In 200 g of a concentrated solution of 70.4 wt% nitric acid (r = 1.41 g/mL, FW(HNO3) = 63.01 g/mol), how many grams of water are
mars1129 [50]

Answer:

59.2 grams

Explanation:

We are given that 70.4% of the weight of the total 200 g of the concentration is made up of nitric acid, the remaining information is not required to solve the problem. Since water and nitric acid are the only components of the solution, the total weight of water is given by:

W = 200*(1-0.704)\\W=59.2\ g

There are 59.2 grams of water in this solution.

5 0
2 years ago
Which feature defines a neutral atom? (1 point)
harina [27]

  • The features  which gives the definition of neutral atom is : the numbers of electrons is equal to number of protons

  • Atoms can be regarded as neutral atom when they has same number of protons and the same numbers of electrons. Even after formation of the ion, there will still be the same number of protons.

  • Example of this is  sodium atom, which has 11 protons as well as  11 electrons

Therefore, number of electrons will be the same as the number of protons as regards neutral atom

Learn more at : brainly.com/question/1641336?referrer=searchResults

7 0
1 year ago
Read 2 more answers
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