Respuesta :
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.
23 would be
B) Endothermic reaction
because it is hotter than its surroundings