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Vsevolod [243]
3 years ago
14

Suppose that a laboratory analysis of white powder showed 42.59% Na, 12.02% C, and 44.99% oxygen. Would you report that the comp

ound is sodium oxalate or sodium carbonate? (Use 43.38% Na, 11.33% C, and 45.29% O for sodium carbonate, and 34.31% Na, 17.93% C, and 47.76% O for sodium oxalate.)
Chemistry
1 answer:
butalik [34]3 years ago
8 0

Answer:

The white powder is sodium carbonate

Explanation:

If you supposed an ammount of 100 grams of the white powder,  it means there are 42.59 grams of Na, 12.02 grams of C and 44.99 grams of O. If you divided every compound by its molar mass, you will know the moles of every compound. (According to moles=mass (grams)/ molar mass (grams/mole)

C=12.01 g/mole, Na=23 g/mole, O=16 g/mole

So:

C=12.02/12.01= 1.0 moles, Na=42.59/ 23= 1.85 moles, O= 44.99/16= 2.81 moles

Knowing this, we can stimated that the white powder has 1 mol of C and approximately 2 and 3 moles of N and O, respectively

Chemical formula for sodium carbonate is Na2CO3 and the formula for sodium oxalate is Na2C2O4. So the white powder is Na2CO3

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1. Something must have mass in order to create change.
nignag [31]

These are three questions each with its complete answer.

Question 1. Something must have mass in order to create change.

A. True

B. False

Answer:

  • <u><em>False</em></u>

Explanation:

Two counter examples will prove that the statement is false.

  • light and fire

Neither light nor fire have mass, so they are not considered matter, but yet both can create changes.

Light is an electromagnetic wave, so it is energy, and as such it, of course, can cause some changes. One example are the chemical reactions, like photosynthesis, which require light to happen.

Ligth may also be described either as quanta named photons. Although photons behave like particles they do not have mass.

So, that example contradicts the statement that something must have mass in order to create change.

Fire also contradicts the statement. Fire is a manifestation of energy, it does not have mass, and sure you know how fire create changes in living and no living things.

Question 2. Powdered medicine fills a pill capsule. Which of the following is the best description of the state of the powder?

A. It is a solid because all powders are solid.

B. It is a gas because it takes up the entire volume of the pill capsule.

C. It is a liquid because it does not hold a definite shape.

Answer: the best description is the choice A:

  • A. It is a solid because all powders are solid.

Explanation:

Indeed, although sometimes the powder may be very fine (dust), yet it is not liquid or gas. Powders are always solid.

There are four main states of matter: solid, liquid, gas, and plasma.

Liquids are able to take the form of the container but do not occupy the entire container. Gases do occupy the entire container.

When powder is very fine it could resemble some properties of liquid, but the structure of powders is not crystaline, this is it is not an ordered arrangement. The structure of powders is an ordered arrangement, so powders are solids and not liquids.

It is easy to discard that a powdered medicine could be a gas, because it definetly do not occupy the entire volume of the pill capsule.

Question 3. Find an example of something that you do NOT know the state of. Describe it, and tell me your best guess of what state it is. Explain your guess.

Answer:

Two examples come to my mind:

  • A paste like Nutella or toothpaste

  • Wax of a candle

Explanation:

I will use the example of Nutella to complete the answer.

Nutella is not a gas because when you open the jar it will not escape and fill the room around it.

When you put Nutella in a plate it will not flow over the whole plate, is it a solid ? But yet you can spread it easyly over a cookie. Is it a liquid?

So, Nutella behaves like a solid until you apply some force over it and then it seems a liquid.

I would guess that pastes are solids because they should have an inner structure that keep the particles together.

If you do some research you will find that pastes are neither liquid nor solids, they are named gels. And gels may be seen as a dispersion of molecules of a liquid within a solid, i.e. in liquid particles dispersed in the solid medium

This sure meets the requirements of this question.

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3 years ago
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Not sure if this is correct but i would choose the steel tray.

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konstantin123 [22]

Answer:

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You could get extremely hurt if you are not wearing goggles while doing lab work.

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