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vladimir1956 [14]
2 years ago
10

What is the pH of 40.0 mL of a solution that is 0.15 M in CN� and 0.29 M in HCN? For HCN, use Ka = 4.9 * 10^-9

Chemistry
1 answer:
artcher [175]2 years ago
4 0
This is a buffer solution because it consists of a weak acid (HCN) and its conjugate base (CN-)
Since it's a buffer solution, the pH is equal to the pKa of the solution, you would use the henderson-hasslebach equation:
pH = pKa - log([acid]/[base])
pH = -log(4.9*10-9) - log(.29/.15)
pH = about 8
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Calculate the number of moles in 24.18 liters of neon gas at STP.
uranmaximum [27]

The number of moles of Neon gas : 1.079

<h3>Further explanation</h3>

Given

24.18 Liters of Neon gas at STP

Required

The number of moles

Solution

There are 2 conditions that are usually used as a reference in chemical calculations (mainly for determining the volume per mole of a gas or the molar volume), STP and RTP

Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure). At STP, Vm is 22.4 liters / mol.

So mol for 24.18 L :

= 24.18 : 22.4

= 1.079 moles

8 0
3 years ago
A chemist measures the energy change ?H during the following reaction: 2HgO (s) ?2Hg (l) +O2 (g) =?H182.kJ Use the information t
Leni [432]

Answer:

The reaction is endothermic.

Yes, absorbed

3.06x10¹kJ are absorbed

Explanation:

In the reaction:

2HgO(s) → 2Hg(l) + O₂(g) ΔH = 182kJ

As ΔH >0,

<em>The reaction is endothermic</em>

<em />

As the reaction is endothermic, when the reaction occurs,

<em>the heat is absorbed.</em>

<em></em>

Now, based on the equation, when 2 moles of HgO (Molar mass: 216.59g/mol), 182kJ are absorbed.

72.8g are:

72.8g * (1mol / 216.59g) = 0.3361 moles HgO.

that absorb:

0.3361 moles HgO * (182kJ / 2 moles) =

<h3>3.06x10¹kJ are absorbed</h3>
8 0
3 years ago
What are 3 examples of physical change?
bazaltina [42]

Just breaking stuff so yea that’s it

3 0
3 years ago
An inventor claims to have developed a new perfume that lasts a long time because it doesn't evaporate. Comment on this claim.
zaharov [31]

Answer:

C

Explanation:

Perfume needs to evaporate in order to smell.  If this perfume didn't evaporate, it would stay as a liquid and never smell.  

It wouldn't be D, as no toxic perfumes is sold.

It's not A because perfume doesn't have to be pressurized in order to not evaporate.

It's not B, as it is a hasty conclusion to the claim.  Plus, if the perfume did have an odor, even while not evaporating, the sales would be low as the product is that good.  

3 0
2 years ago
Summary of a trade-off between. Potential and kinetic energy
uranmaximum [27]
Simply put, Potential energy is the "build up". If I had a ball on the top a 5ft slide, it would have potential energy, as long as it hasn't slid down yet.

If I had another ball on a 10ft slide, it would have twice the potential energy the first ball had.

What comes next is kinetic energy, which is the energy used when the object is moving, like the ball as it goes down the slide. The faster it moves, the more kinetic energy. 

Basically, <em>Potential</em> is the "build up" but it does not, I repeat does not move.

<em>Kinetic</em> energy is the use of the "build up" through movement.
<span>
</span>
7 0
3 years ago
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