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PolarNik [594]
3 years ago
6

Which of th following is an example of how scientist might use a model?

Chemistry
1 answer:
Gemiola [76]3 years ago
8 0
C. marbles placed inside hollow sphere
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Why do we need neutrons in the nucleus?
prohojiy [21]

Answer:

Neutrons are required for the stability of nuclei, with the exception of the single-proton hydrogen nucleus. Neutrons are produced copiously in nuclear fission and fusion. They are a primary contributor to the nucleosynthesis of chemical elements within stars through fission, fusion, and neutron capture processes.

5 0
2 years ago
A chemistry student needs to standardize a fresh solution of sodium hydroxide. He carefully weighs out 28.mg of oxalic acid H2C2
Nezavi [6.7K]

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)

\frac{2}{1} =\frac{x}{2.52}\\ \\ \\x=0.000311(2)=0.000622

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.

5 0
3 years ago
Read 2 more answers
Whats between -999 and 1000
Doss [256]
Hello!

Numbers from -998 and 999 are in between -999 and 1000.

I hope this was helpful! c:
7 0
3 years ago
What pressure is exerted by 0.883 mol N, in a 4.68 L steel container at 197.9 °C?
SpyIntel [72]

I really hope i helped you! :)

6 0
2 years ago
Lead(II) nitrate, Pb(NO3)2, and potassium iodide, KI<br><br><br> net ionic equation:
MissTica

Answer:

Pb²⁺ (aq) + 2I⁻ (aq) → PbI₂ (s)

General Formulas and Concepts:

  • Solubility Rules
  • Reaction Prediction

Explanation:

<u>Step 1: RxN</u>

Pb(NO₃)₂ (aq) + KI (aq) → PbI₂ (s) + KNO₃ (aq)

<u>Step 2: Balance RxN</u>

Pb(NO₃)₂ (aq) + 2KI (aq) → PbI₂ (s) + 2KNO₃ (aq)

<u>Step 3: Ionic Equations</u>

Total Ionic Equation:

Pb²⁺ (aq) + 2NO₃⁻ (aq) + 2K⁺ (aq) + 2I⁻ (aq) → PbI₂ (s) + 2K⁺ (aq) + 2NO₃⁻ (aq)

<em>Cancel out spectator ions.</em>

Net Ionic Equation:

Pb²⁺ (aq) + 2I⁻ (aq) → PbI₂ (s)

7 0
3 years ago
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