1. Why is a homogeneous mixture not considered a pure substance?
<u><em>Answer:</em></u>
- 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?
<em><u>Answer:</u></em>
- There are equal numbers of atoms on both sides.
3. <em>Methane reacts with oxygen then what are the products?</em>
<u><em>Answer:</em></u>
4. Which one of the following is not a homogeneous mixture?
<u><em>Answer:</em></u>
5. The substance is not uniform in appearance and each part of the mixture contains a combination of different ingredients in different ratios.
<u><em>Answer:</em></u>
6. If a solution is saturated, which of these is true?
<u><em>Answer:</em></u>
- More solvent can be dissolved
7. Which of these substances are molecules?
<u><em>Answer:</em></u>
- 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?
<u><em>Answer:</em></u>
- It is uniform in composition.
9. When a solute is added to a solution, why does it remain homogeneous?
<em>Answer:</em>
10. The chemical formula of glucose is C6H12O6, so it is classified as a(n)
<u><em>Answer:</em></u>
11. <em>How many chlorine (Cl) atoms would be in 4 molecules of salt (4 NaCl)?</em>
<u><em>Answer:</em></u>
12. <em>In a solution of salt and water, which component is the solute?</em>
<u><em>Answer:</em></u>
13. These substances are all
H2O2,
Li
, NaCl
, O2
<u><em>Answer:</em></u>
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?
<em>Answer:</em>
15. What is the difference between a compound and a mixture?
<u><em>Answer:</em></u>
- A compound is a pure substance, but a mixture is not.
16. A firework exploding would be an example of a(n) ________.
<u><em>Answer:</em></u>
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.
<em><u>Solution</u></em>
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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