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Zielflug [23.3K]
3 years ago
14

A technician needs 500.0mL of a 0.500 M MgCl2 solution for some lab procedures. The stock bottle is labeled 4.00 M MgCl2. What v

olume in Ml of stock solution should the technician use?
Chemistry
1 answer:
mihalych1998 [28]3 years ago
4 0

Answer:

Explanation:

To solve this problem, we need to obtain the number of moles of the solute we desired to prepare;

    Number of moles  = molarity x volume

Parameters given;

        volume of solution = 500mL  = 0.5L

          molarity of solution = 0.5M

   Number of moles  =  0.5 x 0.5  = 0.25moles

Now to know the volume stock to take;

           Volume of stock = \frac{number of moles }{molarity}

  molarity of stock  = 4M

                 volume  = \frac{0.25}{4}   = 0.0625L or 62.5mL

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For the reaction a2 + b2 → 2ab, ea(fwd) = 105 kj/mol and ea(rev) = 77 kj/mol. assuming the reaction occurs in one step, calculat
Lady bird [3.3K]
Answer is: 28 kJ.
Chemical reaction: A₂ + B₂ ⇄ 2AB.
Ea(forward) = 105 kJ/mol.
Ea(reverse) = 77 kJ/mol.
ΔH(reaction) = ?
<span>The enthalpy change of reaction is the change in the energy of the reactants to the products.
</span>ΔH(reaction) = Ea(forward) - Ea(reverse).
ΔH(reaction) = 105 kJ/mol - 77 kJ/mol.
ΔH(reaction) = 28 kJ/mol; this is endothermic reaction (ΔH <span>> 0).</span>

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3 years ago
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Identify the Lewis acid and Lewis base from among the reactants in each of the following equations. Match the words in the left
goldfiish [28.3K]

Answer:

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Hope this helps.

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3 years ago
An aqueous solution contains 0.23 M potassium hypochlorite.
Arturiano [62]

Answer:

0.22 mol HClO, 0.11mol HBr.

0.25mol NH₄Cl, 0.12 mol HCl

Explanation:

A buffer is defined as a mixture in solution between weak acid and its conjugate base or vice versa.

Potassium hypochlorite (KClO) could be seen as conjugate base of HClO (Weak acid). That means the addition of <em>0.22 mol HClO  </em>will convert the solution in a buffer. HBr reacts with KClO producing HClO, thus, <em>0.11mol HBr</em> will, also, convert the solution in a buffer. 0.23 mol HBr will react completely with KClO and in the solution you will have only HClO, no a buffering system.

Ammonia (NH₃) is a weak base and its conjugate base is NH₄⁺. That means the addition of <em>0.25mol NH₄Cl</em> will convert the solution in a buffer. Also, NH₃ reacts with HCl producing NH₄⁺. Thus, addition of<em> 0.12 mol HCl</em>  will produce NH₄⁺. 0.25mol HCl consume all NH₃.

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Rzqust [24]

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