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3 years ago

Write a sentence that descrices how to determine the number of moles of a compound in known mass of a

Chemistry

1 answer:

sattari [20]3 years ago

6 0

Explanation:

<u>Moles is denoted by given mass divided by the molecular mass , </u>

Hence ,

n = w / m

n = moles ,

w = given mass ,

m = molecular mass .

For example ,

For a compound X ,

The given mass i.e. w = 20 g

and the molecular mass ,i.e. , m = 10 g / mol

Then the moles can easily be calculated by using the above formula ,

n = w / m

n = 20 g / 10 g/mol = 2 mol

Hence , answer = 2 mol.

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How many grams of oxygen gas will react completely with a block of calcium metal that is 3.0 cm by 3.5 cm by 4.2 cm, if the dens

irina1246 [14]

First find the mass

44.1 ml @ 1.55 g/mL = 68.355 grams of Ca

the equation

Ca + O2 → CaO

= 55 grams of O2

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3 years ago

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What type of bond is H2Se

Vinvika [58]

Answer:The lone pair of electrons takes up more space than a regular bonding pair since it it is not confined to be between two atoms, so it adds coulombic repulsion to the bonding pairs and compresses the angle. Therefore, the bond angle is less than the standard 109.5∘ . It is actually 97.7∘

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3 years ago

The buffer solution is used to control the pH to insure that it does not become too high because excessively basic solutions cou

oksian1 [2.3K]

Answer:

pH = 12.7

Explanation:

First, we have to calculate the [Ca²⁺] in a solution of about 250 ppm CaCO₃.

$\frac{250mgCaCO_{3}}{L} .\frac{1gCaCO_{3}}{1000mgCaCO_{3}} .\frac{1molCa^{2+} }{100gCaCO_{3}} =2.5 \times 10^{-3} M$

Now, let's consider the dissolution of Ca(OH)₂ in water.

Ca(OH)₂(s) ⇄ Ca²⁺(aq) + 2 OH⁻(aq)

The solubility product Ksp is:

Ksp = [Ca²⁺] × [OH⁻]²

[OH⁻] = √(Ksp/[Ca²⁺]) = √(6.5 × 10⁻⁶/2.5 × 10⁻³) = 5.1 × 10⁻² M

Finally, we can calculate pOH and pH.

pOH = -log [OH⁻] = -log (5.1 × 10⁻²) = 1.3

pH + pOH = 14 ⇒ pH = 14 - pOH = 14 - 1.3 = 12.7

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3 years ago

Which option is true about the effect of polarity on solubility?

Alex777 [14]

Explanation:

It is known that like dissolves like. Therefore, polar solutes are soluble in polar solvents.

For example, salt is a polar compound and water is a polar solvent. Therefore, salt will dissolve in water.

On the other hand, oil is an inorganic solvent and hence, it is unable to dissolve any polar solute.

Therefore, we can conclude that following is true about the effect of polarity on solubility.

<em>Polar solutes dissolve better in water than in oil.</em>

<em>Polar solutes have the greatest solubility in polar solvents.</em>

<em><u>Hope this helps!</u></em>

<em><u>Please mark brainliest!</u></em>

5 0

3 years ago

Which element forms an ionic compound when it reacts with lithium?

creativ13 [48]

<h3>Answer:</h3>

Br (Bromine)

<h3>Explanation:</h3>

Li and K,

As the electronegativity difference between Li and K is less than 1.7 therefore, ionic bond cannot form between these two metals.

Li and Fe,

The electronegativity difference is less than 1.7 so neither electron loss nor electron gaining will take place between these two metals. Therefore, there will be no ionic bond between them.

Li and Kr,

As Krypton is a noble gas and does not react due to complete octet hence the formation of KrLi is difficult. However, Krypton can make compounds like KrF₂ e.t.c. Therefore we can skip this option.

For Li and K,

E.N of Bromine = 2.96

E.N of Lithium = 0.98

________

E.N Difference 1.98 (Ionic)

This ionic compound is possible and is the correct option because ionic compounds are always made by metals and non metals and here the combination is perfect.

<h3>Conclusion:</h3>

Lithium (a metal) and form Ionic bond with Bromine (a non metal)

4 0

3 years ago

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