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Boron occurs naturally as two isotopes. What is the difference between these isotopes?

Citrus2011 [14]

<span>"They have different numbers of neutrons and different mass numbers. Remember mass number is protons plus neutrons. The number of protons for an element will never change, however the number of neutrons can." I took the test, its D</span>

6 0

3 years ago

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Groundwater in Pherric, New Mexico, initially contains 1.800 mg/L of iron as Fe3+. What must the pH be raised to in order to pre

xenn [34]

Answer : The pH will be, 3.2

Explanation :

As we known that the value of solubility constant of ferric hydroxide at $25^oC$ is, $2.79\times 10^{-39}$

Amount or solubility of iron consumed = (1.800 - 0.3) mg/L = 1.5 mg/L

The given solubility of iron convert from mg/L to mol/L.

$1.5mg/L=\frac{1.5\times 10^{-3}g/L}{56g/mol}=2.7\times 10^{-7}mol/L$

The chemical reaction will be:

$Fe(OH)_3\rightarrow Fe^{3+}+3OH^-$

The expression of solubility constant will be:

$K_{sp}=[Fe^{3+}]\times [3OH^-]^3$

Now put all the given values in this expression, we get the concentration of hydroxide ion.

$2.79\times 10^{-39}=(2.7\times 10^{-7})\times [3OH^-]^3$

$[OH^-]=1.5\times 10^{-11}M$

Now we have to calculate the pOH.

$pOH=-\log [OH^-]$

$pOH=-\log (1.5\times 10^{-11})$

$pOH=10.8$

Now we have to calculate the pH.

$pH+pOH=14\\\\pH=14-pOH\\\\pH=14-10.8\\\\pH=3.2$

Therefore, the pH will be, 3.2

4 0

3 years ago

A voltaic cell consists of a nickel electrode in a solution containing Ni2+ ions, and a copper electrode in a solution containin

Marysya12 [62]

First, we write the half equations for the reduction of the chemical species present:

Cu⁺² + 2e → Cu; E° = 0.34 V
Ni⁺² + 2e → Ni; E° = - 0.23 V

In order to determine the potential of the cell, we find the difference between the two values. For this:

E(cell) = 0.34 - (-0.23)
E(cell) = 0.57 V

The second option is correct. (The difference in values is due to different values in literature, and it is negligible)

4 0

3 years ago

When should you<br> use a fume hood?

AfilCa [17]

Answer:

if you are working with hazardous materials.

Explanation:

A properly operating and correctly used fume hood can reduce or eliminate exposure to volatile liquids, dusts, and mists. It is advisable to use a laboratory hood when working with all hazardous substances.

4 0

3 years ago

Consider the combustion of glucose: c6h12o6(s) + 6 o2(g) ←→ 6 co2(g) + 6 h2o(g) ∆h = −2, 800 kj/mol which condition i) adding mo

Verizon [17]

The answer is iii) decreasing the pressure of the system. When the pressure is decreased, the equilibrium will shift to the right because it has 12 moles of gas which is greater than the number of moles of gas on the left side, which is 6 moles. Equilibrium shifting to the side that exerts greater pressure is favored to offset the decrease in pressure.

6 0

3 years ago