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4 years ago

Please help. Last grade of this class

Chemistry

1 answer:

Marat540 [252]4 years ago

5 0

Answer: Question 3

Group 14, Period 3 is a metalloid

Explanation: Question 3

The element in group 14, period 3 on the periodic table is Si. Metalloids are elements which share both non-metallic and metallic characteristics.

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14. An enzyme-catalyzed reaction was carried out with the substrate concentration initially a thousand times greater than the Km

emmainna [20.7K]

Answer:

27 min

Explanation:

The kinetics of an enzyme-catalyzed reaction can be determined by the equation of Michaelis-Menten:

$v = \frac{vmax[S]}{Km + [S]}$

Where v is the velocity in the equilibrium, vmax is the maximum velocity of the reaction (which is directed proportionally of the amount of the enzyme), Km is the equilibrium constant and [S] is the concentration of the substrate.

So, initially, the velocity of the formation of the substrate is 12μmol/9min = 1.33 μmol/min

If Km is a thousand times smaller then [S], then

v = vmax[S]/[S]

v = vmax

vmax = 1.33 μmol/min

For the new experiment, with one-third of the enzyme, the maximum velocity must be one third too, so:

vmax = 1.33/3 = 0.443 μmol/min

Km will still be much smaller then [S], so

v = vmax

v = 0.443 μmol/min

For 12 μmol formed:

0.443 = 12/t

t = 12/0.443

t = 27 min

7 0

3 years ago

In an aqueous solution, 42% of a substance dissociates to release hydronium ions. Which of the following statements is true for

const2013 [10]

Answer: The statement it is a weak acid is true for the substance.

Explanation:

An acid that dissociates completely when dissolved in water to give hydrogen $(H^{+})$ or hydronium $(H_{3}O^{+})$ ions is called a strong acid.

For example, HCl is a strong acid.

$HCl + H_{2}O \rightarrow H_{3}O^{+} + Cl^{-}$

An acid that dissociates partially or weakly when dissolved in water to given hydrogen or hydronium ions is called a weak acid.

For example, $CH_{3}COOH$ is a weak acid.

$CH_{3}COOH \rightleftharpoons CH_{3}COO^{-} + H_{3}O^{+}$

A strong base is a base which when dissolved in water then it dissociates completely to give hydroxide ions.

For example, NaOH is a strong acid.

A weak base is a base which when dissolved in water then it dissociates partially or weakly to give hydroxide ions.

For example, $NH_{3}$ is a weak base.

Hence, in an aqueous solution where 42% of a substance dissociates to release hydronium ions shows that the dissociation is less than 50%. This means that substance is dissociating weakly so, it is a weak acid.

Thus, we can conclude that the statement it is a weak acid is true for the substance.

5 0

3 years ago

Some chemicals which are used to control weeds may be harmful to the environment.<br> TrueFalse

pshichka [43]

Probably true because chemicals do control weed and it hurts the environment.

6 0

1 year ago

In most lewis dot structures of neutral compounds, carbon as the central atom will be bound to a maximum of how many atoms, nitr

Fittoniya [83]

The total number of elements that one particular element can bond to can be determined by simply drawing the Lewis structure of the element.

Place the chemical symbol
Then look at the group number = valence electrons
Distribute the valence electrons around the atom.

C = 4 bonds
N = 3 bonds
O = 2 bonds

7 0

3 years ago

Please help me to answer this question.<br>i have to submit tomorrow.

ratelena [41]

Answer:

The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.

4 0

3 years ago