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lions [1.4K]
3 years ago
5

I have some question on Alef website

Chemistry
2 answers:
elena55 [62]3 years ago
5 0

Answer: lava, crater

Explanation:

Pani-rosa [81]3 years ago
4 0

Answer:

A,E

Explanation:

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A sample of water at 100°C is converted to steam after absorbing 820 kJ of heat. How grams of H2O are contained in the sample? A
Varvara68 [4.7K]
Since water is already at 100<span>°C all the energy is used to evaporate it. 
Now we can calculate how many </span>mols of water are evaporated with 820kJ.
N= \frac{820}{41} =20 mol
We calculated that we got 20 mols of water evaporated. Now, all we have to do is find how many grams is a mol of water. Molar mass of water is <span>20.16 g/mol.
</span>The final answer is:
m=20*20.16=403.2g




7 0
3 years ago
Agitation prevents settling in a?
VashaNatasha [74]
D gaseous mixture I hope it helps
5 0
3 years ago
A buffer solution contains 0.345 M acetic acid and 0.377 M sodium acetate . If 0.0613 moles of potassium hydroxide are added to
melamori03 [73]

Answer:

pH = 5.54

Explanation:

The pH of a buffer solution is given by the <em>Henderson-Hasselbach (H-H) equation</em>:

  • pH = pKa + log\frac{[CH_3COO^-]}{[CH_3COOH]}

For acetic acid, pKa = 4.75.

We <u>calculate the original number of moles for acetic acid and acetate</u>, using the <em>given concentrations and volume</em>:

  • CH₃COO⁻ ⇒ 0.377 M * 0.250 L = 0.0942 mol CH₃COO⁻
  • CH₃COOH ⇒ 0.345 M * 0.250 L = 0.0862 mol CH₃COOH

The number of CH₃COO⁻ moles will increase with the added moles of KOH while the number of CH₃COOH moles will decrease by the same amount.

Now we use the H-H equation to <u>calculate the new pH</u>, by using the <em>new concentrations</em>:

  • pH = 4.75 + log\frac{(0.0942+0.0613)mol/0.250L}{(0.0862-0.0613)mol/0.250L} = 5.54
6 0
3 years ago
If the reaction 2HgO --&gt; 2Hg + O2 is endothermic, which bonds are the strongest?
Alika [10]
  • Endothermic reaction means the reactant side takes heat from surrounding and get decomposed i.e ∆H=-ve
  • If the equation is exothermic then it means the reactant is happy to decompose .But it's not as it's endothermic

Now

  • HgO is Omitted from our solution option.

Hg is a atom so no bonds hence no bond strength occurs.

  • O_2 is a molecule and so it's our answer .
3 0
2 years ago
a sample of a compound contains 60gC and 5.05gH.it molar mass is 78.12g/mol what is the compound molecular formula
elena55 [62]
(60)/(60+5.05)=.922367 C
1-0.922367=0.07763259 H
(0.922367)(78.12)=72.05534204 C
(0.07763259)(78.12)=6.06 H
72.05534204/(12.01)=6 C
6.06/1.01=6 H
Empirical= CH
Molecular=C6H6
5 0
3 years ago
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