<span>A chemical element is a pure substance that consists entirely of one type of atom. - Atoms of the same element that differ in the number of neutrons are called isotopes. ... The atoms in compounds are held together by chemical bonds. Electrons that are available to form bonds are called valence electrons.</span>
1) The particles move faster
2) Heat energy also makes it hotter
Answer:
3.71%
Explanation:
The phenolphthalein endpoint refers to the reactions:
OH⁻ + H⁺ → H₂O
CO₃⁻² + H⁺ → HCO₃⁻
While the methyl orange endpoint to:
HCO₃⁻ + H⁺ → H₂CO₃
So the <em>additional volume required for the second endpoint tells us the amount of HCO₃⁻ species</em>, which in turn is the total amount of Na₂CO₃ in the sample:
0.700 mL * 0.100 M * = 0.07 mmol HCO₃⁻
Now <u>we calculate the mass of Na₂CO₃</u>, using its molecular weight:
0.07 mmol HCO₃⁻ = 0.07 mmol Na₂CO₃
0.07 mmol Na₂CO₃ * 106 mg/mmol = 7.42 mg Na₂CO₃
No calculations using the volume of the first equivalence point are required because the problem already tells us the mass of the sample is 0.200 g.
0.200 g ⇒ 0.200 * 1000 = 200 mg
%Na₂CO₃ = 7.42 mg/200 mg * 100 = 3.71%
When determining the percentage by mass of a solution, the mass of the solvent is measured last.
<h3>What is the percentage by mass of a solvent?</h3>
The percentage by mass of a solvent in a solution is the ratio of the mass of the solvent and the mass of the entire solution.
Mathematically, this can be expressed as:
Percentage by mass of solvent = mass of solvent/mass of solution x 100
Thus, given a solution, a weighing balance, an evaporating dish, and a burner:
- The mass of the evaporating dish is determined first (A)
- The mass of the evaporating dish and the solution next (B)
- Next would be to heat the solution to remove the solvent.
- The mass of the evaporating dish plus the residue is then measured (C).
Thereafter, the amount of solvent can then be determined as: (A+B) - C.
More on percentage by mass can be found here: brainly.com/question/16885872
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