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3 years ago

1.If we can see something, it MUST be matter. true or false

Chemistry

2 answers:

sasho [114]3 years ago

5 0

Answer:

False

Explanation:

an example of this would be a rainbow, and a reflection

Hope this helps

weeeeeb [17]3 years ago

3 0

Answer:

False

Explanation:

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there it is fella tried on ma own consciousness

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Troyanec [42]

The wick and the wax

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A solution of potassium cyanide, KCN, is made by dissolving 3.2 g of KCN in water. When this solution reacts with excess hydroch

Rama09 [41]

Answer:

22.7%

Explanation:

We must first put down the equation of reaction to guide our work while solving the problem.

KCN(aq) + HCl (aq)--> KCl(aq) + HCN(aq)

The questions specifically state that HCl is in excess so KCN is the limiting reactant.

Number of moles of KCN reacted= mass of KCN reacted / molar mass of KCN

Mass of KCN reacted= 3.2 g

Molar mass of KCN= 65.12 g/mol

Number of moles of KCN= 3.2/65.12 g/mol= 0.049 moles

Theoretical yield of HCN is obtained thus;

From the reaction equation;

1 mol of KCN produced 1 mole of HCN thus 0.049 moles of KCN will produce 0.049 moles of HCN.

Mass of HCN = number of moles ×molar mass

Molar mass of HCN= 27.0253 g/mol

Hence mass of HCN produced= 0.049mol × 27.0253 g/mol= 1.32g of HCN

Actual yield of HCN= 0.30g

% yield= actual yield/ theoretical yield ×100

% yield= 0.30/1.32 ×100

%yield= 22.7%

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3 years ago

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Please help :) ill mark you as the brainiest hope you have a good day

Hitman42 [59]

Have a wonderful day :) thanks for the points

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3 years ago

Sodium carbonate (NaCO3) is sometimes used as a water-softening agent. Suppose that a worker prepares a 0.730 M solution of NaCO

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The molarity of a solution is the number of moles of a substance divided by the volume in liters prepared.

$molarity=\frac{n}{V}$ , where n is number of moles and V is the volume in liters.

In order to calculate the mass of solute we need to convert the volume and molarity to moles

$1.421 L solution \times\frac{0.0730 moles}{1 Lsolution}= 1.037 mol NaCO_3$

Now that we have moles we use the relative formula mass of NaCO₃, We have 1 Na atom, 1 C atom and 3 O atoms, thus

$M_r= (1\times 22.99) + (1\times 12.00) + (3\times 16.00)= 82.99g/mol$

$1.037 \times\frac{82.99g}{mol} = 86.1g$

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