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3 years ago

One of the earliest atomic models was suggested by John Dalton in the early 1800s.

Chemistry

1 answer:

Nonamiya [84]3 years ago

7 0

Answer:

D. Atoms are like solid balls

Explanation:

John Dalton proposed that all matter is composed of very small things which he called atoms. This was not a completely new concept as the ancient Greeks (notably Democritus) had proposed that all matter is composed of small, indivisible (cannot be divided) objects. When Dalton proposed his model electrons and the nucleus were unknown.

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The activation barrier for the hydrolysis of sucrose into glucose and fructose is 108 kJ/mol. Part A If an enzyme increases the

emmasim [6.3K]

Answer:

The barrier has to be 34.23 kJ/mol lower when the sucrose is in the active site of the enzyme

Explanation:

From the given information:

The activation barrier for the hydrolysis of sucrose into glucose and fructose is 108 kJ/mol.

In this same concentration for the glucose and fructose; the reaction rate can be calculated by the rate factor which can be illustrated from the Arrhenius equation;

Rate factor in the absence of catalyst:

$k_1= A*e^{^{^{ \dfrac {- Ea_1}{RT}}$

Rate factor in the presence of catalyst:

$k_2= A*e^{^{^{ \dfrac {- Ea_2}{RT}}$

Assuming the catalyzed reaction and the uncatalyzed reaction are taking place at the same temperature :

Then;

the ratio of the rate factors can be expressed as:

$\dfrac{k_2}{k_1}={ \dfrac {e^{ \dfrac {- Ea_2}{RT} }} { e^{ \dfrac {- Ea_1}{RT} }}$

$\dfrac{k_2}{k_1}={ \dfrac {e^{[ Ea_1 - Ea_2 ] }}{RT} }}$

Thus;

$Ea_1-Ea_2 = RT In \dfrac{k_2}{k_1}$

Let say the assumed temperature = 25° C

= (25+ 273)K

= 298 K

Then ;

$Ea_1-Ea_2 = 8.314 \ J/mol/K * 298 \ K * In (10^6)$

$Ea_1-Ea_2 = 34228.92 \ J/mol$

$\mathbf{Ea_1-Ea_2 = 34.23 \ kJ/mol}$

The barrier has to be 34.23 kJ/mol lower when the sucrose is in the active site of the enzyme

8 0

3 years ago

!!!PLEASE HELP!!!!

Lynna [10]

Answer: B

Explanation: molarity = concentration c= n/V = 0.5 mol/ 0.05 l = 10 mol/l

4 0

3 years ago

HELP!! Please (: I can’t figure out the answers

MrRa [10]

I believe I know the answer to #4
ANSWER: Two moles to a first approximation
*Disclaimer* I'm pretty sure I'm right, but I could be wrong

5 0

3 years ago

What are some limitations of this experiment? How could it be improved?

solong [7]

Answer: Limitation: They may be more expensive and time consuming than lab experiments. Limitation: There is no control over extraneous variables that might bias the results. This makes it difficult for another researcher to replicate the study in exactly the same way.

Explanation:

Hope this helps!

3 0

3 years ago

Read 2 more answers

Boron has an average mass of 10.81. One isotope of boron has a mass of 10.012938 and a relative abundance of 19.80 percent. The

Andrej [43]

The average mass of an atom is calculated with the formula:

average mass = abundance of isotope (1) × mass of isotope (1) + abundance of isotope (2) × mass of isotope (2) + ... an so on

For the boron we have two isotopes, so the formula will become:

average mass of boron = abundance of isotope (1) × mass of isotope (1) + abundance of isotope (2) × mass of isotope (2)

We plug in the values:

10.81 = 0.1980 × 10.012938 + 0.8020 × mass of isotope (2)

10.81 = 1.98 + 0.8020 × mass of isotope (2)

10.81 - 1.98 = 0.8020 × mass of isotope (2)

8.83 = 0.8020 × mass of isotope (2)

mass of isotope (2) = 8.83 / 0.8020

mass of isotope (2) = 11.009975

mass of isotope (1) = 10.012938 (given by the question)

5 0

3 years ago