I don’t understand what this is saying but it says there are no correct answers
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.
Answer: Sodium perchlorate
Answer:
-1960 kJ.
Step-by-step explanation:
C₄H₄O₄(s) + 3O₂(g) ⟶ 2H₂O((ℓ)) + 4CO₂(g) + Energy
There are three energy flows in this reaction.
From combustion + warm water + warm calorimeter = 0
q₁ + q₂ + q₃ = 0
nΔH + mCwΔT + CcalΔT = 0
<em>Data:
</em>
Mass of fumaric acid = 1.1070 g
Mass of water = 1.093 × 10³ g
Cw = 4.184 J·°C⁻¹g⁻¹
T₁ = 21.10 °C
T₂ = 24.52 °C
Ccal = 891.1 J·°C⁻¹
Calculations:
(a) <em>q₁
</em>
n = 1.1070 g × (1 mol/116.07 g)
n = 0.009 537 mol
q₁ = 0.009 537ΔH J
(b) <em>q₂
</em>
ΔT = 24.52 – 21.10
ΔT = 3.42°C
q₂ = 1093 × 4.184 × 3.42
q₂ = 15 640 J
(c) <em>q₃
</em>
q₃ = 891.1 × 3.42
q₃ =3048 J
(d) <em>ΔH</em>
0.009 537ΔH + 15 640 + 3048 = 0
0.009 537ΔH + 18 688 = 0
0.009 537ΔH = -18 688
ΔH = -18 688/0.009 537
ΔH = -1 959 413 J/mol
ΔH = -1960 kJ/mol
This is quite different from the actual value of -1334.70 kJ·mol⁻¹
The two structures at the right of the image are the greatest contributors to the resonance structure of malachite green.
<h3>What is resonance structure?</h3>
In some cases, one single structure is insufficient to explain the properties of a substance. Now, we know that in such cases we have to invoke more than one structure in order to efficiently discuss the chemistry of the compounds in question.
In this case, we can see from the image that the three structures of malachite green are all resonance structures. However, the two structures at the right hand side are the greatest contributors because they are more conjugated. Hence, the two structures at the right of the image are the greatest contributors to the resonance structure of malachite green.
Learn more about resonance structure:brainly.com/question/23287285
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