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3 years ago

Please please help!

Chemistry

1 answer:

ratelena [41]3 years ago

3 0

The mass percent of potassium chloride is 1.386%

<u><em>calculation</em></u>

mass percent = actual mass/ Theoretical mass x 100

Actual mass = 9.35 g

Theoretical mass is calculated as below

Step 1 : write the equation for reaction

KCl + H₂O → KOH + HCl

Step 2: find the moles of H₂O

moles = mass÷ molar mass

The molar mass of H₂O = (2 x1 ) +(16) = 18 g/mol

moles is therefore = 162.98 g÷ 18 g/mol =9.054 moles

Step 3: use the mole ratio to determine the moles of KCl

KCl: H₂O is 1:1 therefore the moles of KCl is also = 9.054 moles

Step 4: find the theoretical mass of KCl

mass = moles x molar mass

from periodic table the molar mass of KCl = 39 +35.5 =74.5 g/mol

mass = 9.054 moles x 74.5 g/mol =674.5 g

Theoretical mass is therefore = 9.35 g/ 674.5 g x 100 = 1.386%

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ololo11 [35]

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Explanation:

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3 years ago

Is the solution containing 0.20 M Pb2 and 0.10 M Cl (Ksp 1.6x105) a) saturated, b) unsaturated, c) at equilibrium, d) none of th

raketka [301]

Answer : The correct option is, (b) unsaturated

Explanation :

Ionic product : It is defined as the product of the concentrations of the ions present in solution raised to the same power by its stoichiometric coefficient in a solution of a salt. This takes place at any concentration. The ionic product is represented as, Q.

Solubility product constant : It is defined as the product of the concentration of the ions present in a solution raised to the power by its stoichiometric coefficient in a solution of a salt. This takes place at equilibrium only. The solubility product constant is represented as, $K__{sp}$ .

Now we have to calculate the ionic product of given solution.

The balanced chemical reaction is,

$PbCl_2(aq)\rightarrow Pb^{2+}(aq)+2Cl^-(aq)$

The expression of ionic product will be,

$Q=[Pb^{2+}][Cl^-]^2$

$Q=(0.20)\times (0.10)^2$

$Q=0.002$

The ionic product of solution is, 0.002

There are three cases for the solubility :

When $Q$ this means that the solution is unsaturated solution and more solid will be dissolve.

When $Q=k_{sp}$ this means that the solution is saturated solution.

When $Q>k_{sp}$ this means that the solution is supersaturated solution and solid will be precipitate.

From this we conclude that the value of $k_{sp}=1.6\times 10^5$ is greater than the ionic product that means the solution is unsaturated solution and more solid will be dissolve.

Hence, the correct option is, (b) unsaturated

6 0

3 years ago

Can someone help me pls I don’t have time Time is almost ran out pls help

pochemuha

Answer:

Can you get a closer picture, then I can help! It looks like it says something on rain, hail and something else. I cant see it though! :)

Explanation:

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3 years ago

If a reaction mixture contains 24 g of Mg and 32 g of O2 , what is the limiting reactant?

Alexxx [7]

This problem is providing the mass of both magnesium metal and oxygen gas and involved in a chemical reaction and asks for the limiting reactant. At the end, it turns out to be identified as magnesium.

<h3>Stoichiometry</h3>

In chemistry, stoichiometry is a widely-used tool we use in order to relate the mass and moles of different chemical substances involved in a chemical reaction. Thus, we consider the following chemical equation between magnesium and oxygen to produce magnesium oxide.

$2Mg+O_2\rightarrow 2MgO$

However, when the mass of the both of the reactants is given, one must identify the limiting reactant as the one producing the least of the moles of the product, which means we can use the given grams of the both of the reactants, their molar masses and mole ratios with the product to obtain the aforementioned:

$24gMg*\frac{1molMg}{24.3gMg}*\frac{2molMgO}{2molMg}=0.988molMgO\\ \\ 32gO_2*\frac{1molO_2}{32.0gO_2}*\frac{2molMgO}{1molO_2}=2molMgO$

Thus, we can evidence how 24 g of magnesium produce the least of the moles of magnesium oxide, fact validating the magnesium as the limiting reactant and the oxygen as the excess one.