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guajiro [1.7K]
3 years ago
9

A cual grupo pertenecen las tierras raras y los elementos representativos??​

Chemistry
1 answer:
lidiya [134]3 years ago
4 0

Answer:

Explanation:

2

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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?

<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>

  • carbon dioxide and water

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

<u><em>Answer:</em></u>

  • 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.

<u><em>Answer:</em></u>

  • heterogeneous mixtures

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>

  • The solute dissolves.

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

<u><em>Answer:</em></u>

  • pure substance.

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

<u><em>Answer:</em></u>

  • 4

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

<u><em>Answer:</em></u>

  • Salt

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

<u><em>Answer:</em></u>

  • 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?

<em>Answer:</em>

  • 5

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>

  • 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.

<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.

 





3 0
3 years ago
Read 2 more answers
How many molecules are in 92.9 g of NaOH?​
kirza4 [7]

2.3226678127494718

this number you could probably simplify to your own standards on your own.

5 0
3 years ago
What are three methods of measuring the volume of an object?
Anarel [89]
L×w×h=v
length times width times height equals volume
the order in which you multiply does not matter
5 0
3 years ago
Colder air tends to have _____.
iogann1982 [59]

Answer:

I believe the answer is D

Explanation:

C is not correct

8 0
3 years ago
Calculate the volume of one mole of a gas at 1.00 atm pressure and 0 °C.
N76 [4]

Answer:

Solution:-

The gas is in the standard temperature and pressure condition i.e. at S.T.P

Therefore,

V

i

​

=22.4dm

3

V

f

​

=?

As given that the expansion is isothermal and reversible

∴ΔU=0

Now from first law of thermodynamics,

ΔU=q+w

∵ΔU=0

∴q=–w

Given that the heat is absorbed.

∴q=1000cal

⇒w=−q=−1000cal

Now,

Work done in a reversible isothermal expansion is given by-

w=−nRTln(

V

i

​

V

f

​

​

)

Given:-

T=0℃=273K

n=1 mol

∴1000=−nRTln(

V

i

​

V

f

​

​

)

⇒1000=−1×2.303×2×273×log(

22.4

V

f

​

​

)

Explanation:

6 0
2 years ago
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