Answer:
- The molarity of the student's sodium hydroxide solution is 0.0219 M
Explanation:
<u>1) Chemical reaction.</u>
a) Kind of reaction: neutralization
b) General form: acid + base → salt + water
c) Word equation:
- sodium hydroxide + oxalic acid → sodium oxalate + water
d) Chemical equation:
- NaOH + H₂C₂O₄ → Na₂C₂O₄ + H₂O
b) Balanced chemical equation:
- 2NaOH + H₂C₂O₄ → Na₂C₂O₄ + 2H₂O
<u>2) Mole ratio</u>
- 2mol Na OH : 1 mol H₂C₂O₄ :1 mol Na₂C₂O₄ : 2 mol H₂O
<u>3) Starting amount of oxalic acid</u>
- mass = 28 mg = 0.028 g
- molar mass = 90.03 g/mol
- Convert mass in grams to number of moles, n:
n = mass in grams / molar mass = 0.028 g / 90.03 g/mol = 0.000311 mol
<u>4) Titration</u>
- Volume of base: 28.4 mL = 0.0248 liter
- Concentration of base: x (unknwon)
- Number of moles of acid: 2.52 mol (calculated above)
- Proportion using the theoretical mole ratio (2mol Na OH : 1 mol H₂C₂O₄)
That means that there are 0.000622 moles of NaOH (solute)
<u>5) Molarity of NaOH solution</u>
- M = n / V (liter) = 0.000622 mol / 0.0284 liter = 0.0219 M
That is the correct number using <em>three signficant figures</em>, such as the starting data are reported.
The answer is: the distance between two nuclei is 2.35×10⁻¹⁰ m.
r(Na⁺) = 1.16×10⁻¹⁰ m; radius of sodium cation.
r(F⁻) = 1.9×10⁻¹⁰ m; radius of fluoride anion.
d(NaF) = r(Na⁺) + r(F⁻).
d(NaF) = 1.16×10⁻¹⁰ m + 1.9×10⁻¹⁰ m.
d(NaF) = 2.35×10⁻¹⁰ m; distance between two nuclei.
The sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice.
Answer:
i dont know i do this for points
Explanation:
Answer: An igneous rock that cools rapidly is made of really small mineral crystals.
Explanation:
The layers inside the earth are hot enough to melt a rock. The liquid or molten rock is known as magma.
When a molten rock cools and solidifies, it results in the formation of an igneous rock.
The slow cooling of magma will result in the formation of an igneous rock with large crystals. Whereas, rapid cooling of lava will result in the formation of an igneous rock with small crystals.
Thus, it can be concluded that an igneous rock that cools rapidly is made of really small mineral crystals.
Answer: the second option: <span>Iron is being oxidized
</span>
Explanation:
1) Oxidation is the increase of the oxidation state (number) due to the loss of electrons.
2) In the given reaction, you can see that in the left side the atom is Fe.
When an element (atom) is not combined (or combined with it self) its oxidation state is 0.
3) In the right side of the given equation you that iron is now in form of cation with charge 2+: Fe²⁺.
That means that the new oxidation state of the element is 2+.
4) This change in the oxidation state, of course, is accompanied by the loss of the two electrons: 2e⁻.
5) Conclusion: the iron has oxidized by losing two electrons and increasing its oxidation state from 0 to 2+.
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