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mr Goodwill [35]
3 years ago
10

Please help me will mark brainly

Chemistry
1 answer:
viva [34]3 years ago
8 0
1. Physical
2. D
3. It’s either A or D but I think it’s A
4. C
5. A
6. D
7. A
8. B
9. I couldn’t see the question for it
10. A
11. D
12. D
13. B
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Calculate the number of moles of ethanol acid in 30 cm³of 1 mol dm-³ solution ​
muminat

Answer:

May I assume "ethanol acid is just ethanol (it has one slightly acidic H atom).  If so, the molar mass is 46.02 g/mole.

Explanation:

We have 30 cm^3 [30 ml] of 1.0 M (1 mole/liter)  [1 dm³ = 1 liter].

That is 1 mole/liter.  30 ml would contain (0.030 liter)*(1 mole/1 liter) = 0.03 moles.

7 0
3 years ago
The acid-dissociation constants of HC3H5O3 and CH3NH3+ are given in the table below. Which of the following mixtures is a buffer
sergey [27]

Answer:

A mixture of 100. mL of 0.1 M HC3H5O3 and 50. mL of NaOH

Explanation:

The pH of a buffer solution is calculated using following relation

pH=pKa+log(\frac{salt}{acid} )

Thus the pH of buffer solution will be near to the pKa of the acid used in making the buffer solution.

The pKa value of HC₃H₅O₃ acid is more closer to required pH = 4 than CH₃NH₃⁺ acid.

pKa = -log [Ka]

For HC₃H₅O₃

pKa = 3.1

For CH₃NH₃⁺

pKa = 10.64

pKb = 14-10.64 = 3.36 [Thus the pKb of this acid is also near to required pH value)

A mixture of 100. mL of 0.1 M HC3H5O3 and 50. mL of NaOH

Half of the acid will get neutralized by the given base and thus will result in equal concentration of both the weak acid and the salt making the pH just equal to the pKa value.

8 0
3 years ago
_____ were common ocean scavengers long ago, and they are frequently found in fossilized form.
quester [9]

Answer:

a. trilobites.

Explanation:

6 0
4 years ago
The lock-and-key model and the induced-fit model are two models of enzyme action explaining both the specificity and the catalyt
ivolga24 [154]

Answer:

The lock-and-key model:

c. Enzyme active site has a rigid structure complementary

The induced-fit model:

a. Enzyme conformation changes when it binds the substrate so the active site fits the substrate.

Common to both The lock-and-key model and The induced-fit model:

b. Substrate binds to the enzyme at the active site, forming an enzyme-substrate complex.

d. Substrate binds to the enzyme through non-covalent interactions

Explanation:

Generally, the catalytic power of enzymes are due to transient covalent bonds formed between an enzyme's catalytic functional group and a substrate as well as non-covalent interactions between substrate and enzyme which lowers the activation energy of the reaction. This applies to both the lock-and-key model as well as induced-fit mode of enzyme catalysis.

The lock and key model of enzyme catalysis and specificity proposes that enzymes are structurally complementary to their substrates such that they fit like a lock and key. This complementary nature of the enzyme and its substrates ensures that only a substrate that is complementary to the enzyme's active site can bind to it for catalysis to proceed. this is known as the specificity of an enzyme to a particular substrate.

The induced-fit mode proposes that binding of substrate to the active site of an enzyme induces conformational changes in the enzyme which better positions various functional groups on the enzyme into the proper position to catalyse the reaction.

4 0
3 years ago
A glass holds 6 ounces of 60-proof rum (30 alcohol). how much fruit juice must be added to the rum so that the mixture is dilute
Elenna [48]

We need an equation that will relate the concentrated mixture and the diluted one. To solve this we use the equation, 

M1 V1 = M2 V2

where M1 is the concentration of the stock solution, V1 is the volume of the stock solution, M2 is the concentration of the new solution and V2 is its volume.

M1V1 = M2V2

30 % x 6 oz = 20 %  x V2

V2 = 9 oz 


The volume of the diluted mixture would be 9 oz. Therefore, you will need to add 9 oz - 6 oz = 3 oz of fruit juice to dilute the 30 percent alcohol to 20 percent alcohol.

7 0
3 years ago
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