Why is the number of electrons or charge of each ion useful information when predicting the products in replacement reactions?

Express the concentration of a 0.0350 M aqueous solution of fluoride, F − , in mass percentage and in parts per million (ppm). A

sveta [45]

Answer :

(a) The mass percentage is 0.0665 %

(b) The concentration in ppm is 665 ppm.

Explanation :

Part (a) :

As we are given that, 0.0350 M aqueous solution of fluoride ion that means 0.0350 moles of fluoride ion present in 1 L of solution.

First we have to calculate the mass of fluoride ion.

$\text{Mass of }F^-=\text{Moles of }F^-\times \text{Molar mass of }F^-$

Molar mass of $F^-$ = 19 g/mole

$\text{Mass of }F^-=0.0350mol\times 19g/mol=0.665g$

Now we have to calculate the mass of solution.

Mass of solution = Density of solution × Volume of solution

Density of solution = 1.00 g/mL

Volume of solution = 1 L = 1000 mL

Mass of solution = 1.00 g/mL × 1000 mL

Mass of solution = 1000 g

Now we have to calculate the mass -percentage.

$\text{Mass of percentage}=\frac{\text{Mass of }F^-}{\text{Mass of solution}}\times 100$

$\text{Mass of percentage}=\frac{0.665g}{1000g}\times 100=0.0665\%$

Thus, the mass percentage is 0.0665 %

Part (b) :

Parts per million (ppm) : It is defined as the mass of a solute present in one million $(10^6)$ parts by the mass of the solution.

Now we have to calculate the concentration in ppm.

$\text{Concentration in ppm}=\frac{\text{Mass of }F^-}{\text{Mass of solution}}\times 10^6$

$\text{Concentration in ppm}=\frac{0.665g}{1000g}\times 10^6=665ppm$

Thus, the concentration in ppm is 665 ppm.

7 0

4 years ago

Molarity and Dilution

Aleonysh [2.5K]

Answer: The moles needed are 0.01.

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

$Molarity=\frac{n\times 1000}{V_s}$

where,

n = moles of solute $(CuSO_4.5H_2O)$ = ?

$V_s$ = volume of solution in ml

Now put all the given values in the formula of molarity, we get

$0.10=\frac{n\times 1000}{100}$

$n=\frac{0.10\times 100}{1000}=0.01$

Therefore, the moles needed are 0.01.

6 0

3 years ago

16 Which change results in the formation of different substances?(1) burning of propane

Trava [24]

1. The burning of propane creates different substances: propane and oxygen combine to create water and carbon dioxide:

C3H8 + 5 O2 becomes 3 CO2 + 4 H2O + heat

2. When NaCl melts, it is changing state, but it is still the same NaCl.

3. When gaseous CO2 deposits it is changing state, but it is still the same CO2.

4. When (presumably liquid) water solidifies, it is changing state, but it is still the same water.

So the answer is 1.

6 0

3 years ago

Read 2 more answers

If an object goes through a chemical reaction but does not change in mass that object has

eimsori [14]

Answer:

The law of conservation of mass

Explanation:

The law of conservation of mass

6 0

2 years ago

Determine the percent yield forthe reaction between 82.4 g of Rband 11.6 g of O2 if 39.7 g of Rb2Ois produced

Mazyrski [523]

Step 1

The reaction is written and balanced:

4 Rb + O2 =>2 Rb2O

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Step 2

Define % yield of product (Rb2O) = (Actual yield/Theoretical yield) x 100

The actual yield is provided by the exercise = 39.7 g

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Step 3

Determine the limiting reactant. The molar masses are needed to solve this:

For Rb) 85.4 g/mol

For O2) 32 g/mol

Procedure:

4 Rb + O2 =>2 Rb2O

4 x 85.4 g Rb ----- 32 g O2

82.4 g Rb ----- X = 7.72 g O2 are needed

For 82.4 g Rb, 7.72 g O2 is needed, but there is 11.6 g O2. Therefore, O2 is the excess agent. Rb is the limiting reactant.

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Step 4

Determine the theoretical yield from the limiting reactant:

The molar mass Rb2O) 187 g/mol

Procedure:

4 x 85.4 g Rb ------ 2 x 187 g Rb2O

82.4 g Rb ------ X = 90.2 g Rb2O = Theoretical yield

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Step 5

% yield = Actual y./Theoretical y. x 100 = (39.7 g/90.2 g) x 100 = 44 % approx.

Answer: % yield = 44 %

4 0

1 year ago