A. chlorine B. sulfur C. oxygen D. none of these

The following does NOT indicate that a chemical change may have taken place is fracture formation. A chemical change happens when the substance changes its physical state and composition resulting from a chemical reaction. This chemical reaction may either give off or absorb energy. A change in color is a chemical change. For example, litmus paper turns to red when placed in an acid solution. Production of gas is a chemical change. For example, adding hydrochloric acid to the tiles of the bathroom gives a hissing sound with gases given off. Formation of a precipitate is also a chemical change. Change in shape is not a chemical change.

3 0

3 years ago

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Why is a homogeneous mixture not considered a pure substance? Question 6 options: A pure substance can be separated by physical

krok68 [10]

1. Why is a homogeneous mixture not considered a pure substance?

Answer:

A pure substance can be separated by chemical means, while a mixture can be separated by physical means.

2. What is true if mass is conserved in a reaction?

Answer:

There are equal numbers of atoms on both sides.

3. Methane reacts with oxygen then what are the products?

Answer:

carbon dioxide and water

4. Which one of the following is not a homogeneous mixture?

Answer:

vegetable soup

5. The substance is not uniform in appearance and each part of the mixture contains a combination of different ingredients in different ratios.

Answer:

heterogeneous mixtures

6. If a solution is saturated, which of these is true?

Answer:

More solvent can be dissolved

7. Which of these substances are molecules?

Answer:

All compounds are molecules but not all molecules are compounds. Molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element. So correct option is 3 and 4.

8. What makes a solution a homogeneous mixture?

Answer:

It is uniform in composition.

9. When a solute is added to a solution, why does it remain homogeneous?

Answer:

The solute dissolves.

10. The chemical formula of glucose is C6H12O6, so it is classified as a(n)

Answer:

pure substance.

11. How many chlorine (Cl) atoms would be in 4 molecules of salt (4 NaCl)?

Answer:

4

12. In a solution of salt and water, which component is the solute?

Answer:

Salt

13. These substances are all H2O2, Li , NaCl , O2

Answer:

Pure Substances

14. If you have 5 grams of product after a chemical reaction, how many grams of reactants did you have at the start of the reaction?

Answer:

5

15. What is the difference between a compound and a mixture?

Answer:

A compound is a pure substance, but a mixture is not.

16. A firework exploding would be an example of a(n) ________.

Answer:

Exothermic reaction

17. If Lavoisier heated 100 grams of powdered mercuric oxide to produce 93 grams of liquid mercury, how much oxygen would be released?

Solution

2HgO ==> 2Hg + O2

Mass of HgO = 100 g

Molar mass of HgO = 216.59 g/mol

Moles = mass/molar mass = 0.46 moles

From balance chemcial equation

HgO : O2

2 = 1

0.46 = (1 × 0.46 ) ÷ 2 = 0.23 moles

mass of O2 = moles× molar mass = 0.23 × 32 = 7.36 g

18. Using the Law of Conservation of Matter, determine the number of grams of iron sulfide (FeS) that will be produced in this reaction.

Solution

12g Fe + 64g S → _____ g FeS

According to Law of Conservation of Matter, The total mass of reactant is equal to total mass of product , so the number of grams of iron sulfide (FeS) that will be produced in this reaction as follow.

12 + 64 = 76 g of FeS

Hope this Help.

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3 years ago

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Caffeine (C8H10N4O2) is a stimulant found in coffees and teas. When dissolved in water, it can accept a proton from a water mole

Olenka [21]

Answer:

See figure 1

Explanation:

If we want to find the acid and the Brønsted-Lowry base, we must remember the definition for each of these molecules:

-) Acid: hydrogen donor

-) Base: hydrogen acceptor

In the caffeine structure, we have several atoms of nitrogen. These nitrogen atoms have the ability to accept hydronium ions ( $H^+$ ). Therefore the caffeine molecule will be the base since it can accept

If caffeine is the base, the water must be the acid. So, the water in this reaction donated a hydronium ion.

Thus, caffeine is the base and water the acid. (See figure 1)

3 0

3 years ago

A. chlorineB. sulfurC. oxygen D. none of these​

A. chlorineB. sulfurC. oxygen D. none of these