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3 years ago

Which of the following is not a catalyst? A. Nickel B. Platinum C. Enzymes D. Phosphorus

Chemistry

2 answers:

Bogdan [553]3 years ago

7 0

Answer:

The correct answer is D. Phosphorus is not a catalyst.

Explanation:

A catalyst is a substance that accelerates a chemical reaction at a certain temperature, but does not itself wear off the reaction. It is involved in the chemical reaction but is not the starting or end product of the reaction.

Catalysts create an alternative reaction pathway for the reaction with a lower activation energy. Activation energy is the energy required for the reaction to take place. However, the catalyst cannot cause a reaction which does not take place without the catalyst.

Depending on the phases in which the catalyst and reactants are present, one speaks of homogeneous or heterogeneous catalysts. Biochemical processes are catalyzed by enzymes, while heterogeneous catalysts are metals, such as platinum and nickel.

Mazyrski [523]3 years ago

6 0

The answer would be D because from my research it's the only one that didn't have a catalyst

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A particular first-order reaction has a rate constant of 1.35 × 102 s-1 at 25.0°c. what is the magnitude of k at 75.0°c if ea =

IgorC [24]

According to this formula:
K= A*(e^(-Ea/RT) when we have K =1.35X10^2 & T= 25+273= 298K &R=0.0821
Ea= 85.6 KJ/mol So by subsitution we can get A:
1.35x10^2 = A*(e^(-85.6/0.0821*298))
1.35x10^2 = A * 0.03
A= 4333
by substitution with the new value of T(75+273) = 348K & A to get the new K
∴K= 4333*(e^(-85.6/0.0821*348)
= 2.16 x10^2

8 0

3 years ago

What is the charge of an atom after it gains an electron during the formation of a bond?

Alex_Xolod [135]

Answer:

D. One negative charge

Explanation:

During the formation of a bond, if an atom gains an electron, after that it will be left with a negative charge compared to the atom before the bond is formed. This is because in these types of bonds, which are ionic bonds, there is a transfer of electrons between atoms, there will be one or more atoms that yield electrons that will be captured by another and other atoms that gain them, and the difference of charges produced by this transfer of electrons, will cause the union to occur due to the attraction between electrostatic forces.

If you have a neutral atom before joining, and it gains an electron to form a bond, it will have one electron more than its initial state (in the initial state, the number of protons and electrons is the same, because the atoms they are electrically neutral), so having an extra electron will make it have a negative charge, since there will be a difference between the number of protons and electrons that the atom possesses. This is why the correct answer is D.

In the case of response A and B, the atom could only remain positively charged if it loses electrons, but as in this case it wins, they are not correct.

The answer C is also not correct because only one electron wins, so that it is left with two negative charges, it should gain two electrons during the bond formation.

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3 years ago

What do atoms when they share electron pairs

ra1l [238]

Covalent bonds I think

3 0

3 years ago

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What is the surface tension of H20

andrew11 [14]

Answer:

the surface tension of H20 is 72 dynes/cm at 25°C

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4 years ago

Read 2 more answers

Explain how you determine the freezing point of a solution that does not have a well-defined transition in the cooling curve.

Sophie [7]

This question is asking for a method for the determination of the freezing point in a solution that does not have a noticeable transition in the cooling curve, which is basically based on a linear fit method.

The first step, would be to understand that when the transition is well-defined as the one on the attached file, we can just identify the temperature by just reading the value on the graph, at the time the slope has a pronounced change. For instance, on the attached, the transition occurs after about 43 seconds and the freezing point will be about 4 °C.

However, when we cannot identify a pronounced change in the slope, it will be necessary to use a linear fit method (such as minimum squares) to figure out the equation for each segmented line having a significantly different slope and then equal them so that we can numerically solve for the intercept.

As an example, imagine two of the segmented lines have the following equations after applying the linear fit method:

$y=-3.5 x + 25\\\\y=-0.52 x + 2$

First of all, we equal them to find the x-value, in this case the time at which the freezing point takes place:

$-3.5 x + 25=-0.52 x + 2\\\\-3.5 x+0.52 x =2-25\\\\x=\frac{-23}{-2.98}=7.72$

Next, we plug it in in any of the trendlines to obtain the freezing point as the y-value:

$y=-3.5 (7.72) + 25\\\\y = 1.84$

This means the freezing point takes place after 7.72 second of cooling and is about 1.84 °C. Now you can replicate it for any not well-defined cooling curve.

Learn more:

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3 years ago