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3 years ago

How many moles of solute are contained in a 250 ml solution that has a concentration of.85 m?

1 answer:

3 0

Volume = 250 mL in liters : 250 / 1000 => 0.25 L

Molarity = 0.85 M

Number of moles:

n = M x V

n = 0.85 x 0.25

n = 0.21 moles

Choice B

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Sodium metal and water react to form hydrogen and sodium hydroxide. If 11.96 g of sodium react with water to form 0.52 g of hydr

Anastasy [175]

Answer:

9.36g of H2O.

Explanation:

We'll begin by writing the balanced equation for the reaction.

2Na + 2H2O —> 2NaOH + H2

Next, we shall determine the mass of Na and H2O that reacted from the balanced equation.

This is illustrated below:

Molar mass of Na = 23g/mol

Mass of Na from the balanced equation = 2 x 23 = 46g

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

Mass of H2O from the balanced equation = 2 x 18 = 36g

From the balanced equation above,

46g of Na reacted with 36g of H2O.

Now, we can determine the mass of H2O involved in reaction as follow:

From the balanced equation above,

46g of Na reacted with 36g of H2O.

Therefore, 11.96g of Na will react with = (11.96 x 36)/46 = 9.36g of H2O.

Therefore, 9.36g of H2O were used for the reaction.

4 0

3 years ago

What is the average of the two weights of a nickel and dime. Dime is 2.26g and nickel is 4.97g?

ANTONII [103]

Dime=2.26g
Nickel=4.97g

$\\ \rm\Rrightarrow Avg\:Weight=\dfrac{Sum\:of\:Weights}{No\:of\:weights}$

$\\ \rm\Rrightarrow Avg\:weight=\dfrac{2.26+4.96}{2}$

$\\ \rm\Rrightarrow Avg\;weight=\dfrac{7.23}{2}$

$\\ \rm\Rrightarrow Avg\:Weight=3.6g$

5 0

2 years ago

5. Which elements are examples of nonmetals?

kykrilka [37]

Answer:

Explanation:

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5 0

2 years ago

In the background information, it was stated that CaF2 has solubility, at room temperature, of 0.00160 g per 100 g of water. How

____ [38]

Answer:

2.05*10⁻⁵ moles of CF₂ can dissolve in 100 g of water.

12.82 moles of CaF₂ will dissolve in exactly 1.00 L of solution

Explanation:

First, by definition of solubility, in 100 g of water there are 0.0016 g of CaF₂. So, to know how many moles are 0.0016 g, you must know the molar mass of the compound. For that you know:

Ca: 40 g/mole
F: 19 g/mole

So the molar mass of CaF₂ is:

CaF₂= 40 g/mole + 2*19 g/mole= 78 g/mole

Now you can apply the following rule of three: if there are 78 grams of CaF₂ in 1 mole, in 0.0016 grams of the compound how many moles are there?

$moles=\frac{0.0016 grams*1 mole}{78 grams}$

moles=2.05*10⁻⁵

2.05*10⁻⁵ moles of CF₂ can dissolve in 100 g of water.

Now, to answer the following question, you can apply the following rule of three: if by definition of density in 1 mL there is 1 g of CaF₂, in 1000 mL (where 1L = 1000mL) how much mass of the compound is there?

$mass of CaF_{2}=\frac{1000 mL*1g}{1mL}$

mass of CaF₂= 1000 g

Now you can apply the following rule of three: if there are 78 grams of CaF₂ in 1 mole, in 1000 grams of the compound how many moles are there?

$moles=\frac{1000 grams*1 mole}{78 grams}$

moles=12.82

12.82 moles of CaF₂ will dissolve in exactly 1.00 L of solution

5 0

3 years ago

How many moles of LiOH are needed to react completely with 25.5 g of CO2

LekaFEV [45]

Answer:

3.18 mol

Explanation:

$2LiOH+CO_{2}-> Li_{2}CO_{3} +H_{2}O$

n(CO2) = mass/ Mr.

= 25.5 / 16

= 1.59 mol

As per the equation above,

n(LiOH) : n(CO2)

2 : 1

∴ 3.18 : 1.59

3 0

2 years ago