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juin [17]
3 years ago
8

What is the concentration of a solution of (a) KOH for which the pH is 11.89; (b) Ca(OH)2 for which the pH is 11.68

Chemistry
1 answer:
zalisa [80]3 years ago
3 0

Answer:

[KOH] = 7.76×10⁻³ M

[Ca(OH)₂] = 2.39×10⁻³ M

Explanation:

KOH → K⁺  +  OH⁻

pH = - log [H⁺]

14 = pH + pOH

pOH = - log [OH⁻]

10^-pOH = [OH⁻]

14 - 11.89 = 2.11 → pOH

2.11 = - log [OH⁻]

10⁻²°¹¹ =  [OH⁻] → 7.76×10⁻³ M  

As ratio is 1:1, [KOH] = 7.76×10⁻³ M

14 - 11.68 = 2.32 → pOH

10⁻²°³² = [OH⁻] → 4.78×10⁻³ M

Ca(OH)₂ → Ca²⁺  +  2OH⁻

Ratio is 2:1, so I will have the half of base.

4.78×10⁻³  /2 = 2.39×10⁻³ M

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The elements which are in between the metals and non-metals can be classified as semi-metals.

Although the conductivity of a material is an inherent property of the metals but sometime the nonmetals or semi-metals are also behave like a conductor due to presence of the other elements, thus it cannot be a p[property of the periodic table. Similarly acidity, flammable gases are not part of the periodic table.      

3 0
3 years ago
2. Matt went to his friend’s party. He ate a big meal and drank a keg of beer. He felt heartburn after the meal and took Tums to
evablogger [386]

Answer:

390.85mL

Explanation:

Step 1:

Data obtained from the question.

Initial pressure (P1) = 780 torr

Initial volume (V1) = 400mL

Initial temperature (T1) = 40°C = 40°C + 273 = 313K

Final temperature (T2) = 25°C = 25°C + 273 = 298K

Final pressure (P2) = 1 atm = 760torr

Final volume (V2) =?

Step 2:

Determination of the final volume i.e the volume of the gas outside Matt's body.

The volume of the gas outside Matt's body can be obtained by using the general gas equation as shown below:

P1V1/T1 = P2V2/T2

780 x 400/313 = 760 x V2 /298

Cross multiply to express in linear form

313 x 760 x V2 = 780 x 400 x 298

Divide both side by 313 x 760

V2 = (780 x 400 x 298) /(313 x 760)

V2 = 390.85mL

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3 0
3 years ago
You are given a solid that is a mixture of na2so4 and k2so4.
Murljashka [212]

Here we have to calculate the amount of SO_{4}^{2-} ion present in the sample.

In the sample solution 0.122g of SO_{4}^{2-} ion is present.

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K₂SO₄ = 2K⁺ +  SO_{4}^{2-}

(Na)₂SO₄=2Na⁺ +  SO_{4}^{2-}

Thus, BaCl₂+  SO_{4}^{2-} = BaSO₄↓ + 2Cl⁻ .

(Na)₂SO₄ and  K₂SO₄ is highly soluble in water and the precipitation or the filtrate is due to the BaSO₄ only. As a precipitation appears due to addition of excess BaCl₂ thus the total amount of  SO_{4}^{2-} ion is precipitated in this reaction.  

The precipitate i.e. barium sulfate (BaSO₄)is formed in the reaction which have the mass 0.298g.

Now the molecular weight of BaSO₄ is 233.3 g/mol.

We know the molecular weight of sulfate ion (SO_{4}^{2-}) is 96.06 g/mol. Thus in 1 mole of BaSO₄ 96.06 g of SO_{4}^{2-} ion is present.

Or. we may write in 233.3 g of BaSO₄ 96.06 g of SO_{4}^{2-} ion is present. So in 1 g of BaSO₄ \frac{96.06}{233.3}=0.411 g of SO_{4}^{2-} ion is present.

Or, in 0.298 g of the filtered mass (0.298×0.411)=0.122g of SO_{4}^{2-} ion is present.        

5 0
3 years ago
A compound is 54.53% c, 9.15% h, and 36.32% o by mass. what is its empirical formula? the molecular mass of the compound is 132
Yakvenalex [24]
 <span>First - you need the empirical formula. 

So, assume you have 100 g of the compound. 

If so, you'll have 54.53 gram of C, 9.15 g of H and 36.32 g of O. Find the number of moles of each. 

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9.15 g H (1 mole H / 1.008 g H) = 9.077 

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Take the smallest number found and divide the others by it to get the empirical formula. 

4.540/2.270 = 2. 
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So, that gives you the empirical formula of C2H4O. 

Find the weight of this compound. C = 12, H = 1, O = 16. So, C2H4O is 44 amu. 

132/44 = 3. 

So, 3 (C2 H4 O) = C6H12O3 = molecular formula.</span>
6 0
4 years ago
Each type of mineral has a chemical composition that is
Rus_ich [418]
Answer: C. variable depending on where its found

The chemical compositions of minerals is very necessary in order to define or describe a certain mineral. Some minerals can be written in simple chemical formula while others are also written in complicated chemical formulas.

7 0
3 years ago
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