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AURORKA [14]
3 years ago
11

Group viia elements are very active non metals give reason​

Chemistry
1 answer:
Marianna [84]3 years ago
4 0

Answer:

because they need only one electron

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A chemist is given a 3.00M solution of KBr and needs to measure out 0.733 moles of this solution. How many mL of the 3.00M KBr s
Charra [1.4K]

In order to measure 0.733 moles of KBr from a 3.00 M solution, the chemist needs 244 mL of solution.

<h3>What is molarity?</h3>

Molarity (M) is a unit of concentration of solutions, and it is defined as the moles of a solute per liters of a solution.

  • Step 1: Calculate the liters of solution required.

A chemist has a 3.00 M KBr solution and wants to measure 0.733 moles of KBr. The required volume is:

0.733 mol × (1 L/3.00 mol) = 0.244 L

  • Step 2: Convert 0.244 L to mL.

We will use the conversion factor 1 L = 1000 mL.

0.244 L × (1000 mL/1 L) = 244 mL

In order to measure 0.733 moles of KBr from a 3.00 M solution, the chemist needs 244 mL of solution.

Learn more about molarity here: brainly.com/question/9118107

7 0
2 years ago
why is H2SO4 considered as strong acid? What colour does it give with phenolphthalein and methyl orange?​
marta [7]

Answer:

H2SO4 (sulphuric acid) is considered a strong acid because it's H+ ions completely dissociates or ionizes in a water. When reacted with phenolphthalein is colourless because phenolphthalein doesn't react with acids, only strong bases and when reacted with methyl orange, it changes from orange to red.

Explanation:

4 0
2 years ago
Phosphoric acid is a triprotic acid with the following pKa values:
lisabon 2012 [21]

Answer:

Mass NaH₂PO₄ = 1.920 g

Mass Na₂HPO₄ = 4.827 g

Explanation:

For a buffer solution we know its pH can be calculated from the Henderson-Hasselbach formula:

pH = pKa + log [A⁻]/[HA]

where [A⁻] and [HA] are the concentrations of the weak acid and its conjugate base in the buffer.

We want to prepare a buffer at pH 7.540 so we have chosen salts NaH₂PO₄ and Na₂HPO₄ as the weak acid and conjugate base respectively.

To calculate the mass of these salts we need to compute their ratio in the Henderson- Hasselbach equation .

Now since we are asked to determine the masses of NaH₂PO₄  and  Na₂HPO₄ and we know we want to prepare 1.000 L of a 0.05 M phosphate buffer, we can setup a system of 2 equations with two unknowns from the ratio mentioned above:

pH = pKa + log [A⁻]/[HA]

7.540 = 7.198 + log[HPO₄²⁻] / [H₂PO₄ ⁻]

0.342 = log[HPO₄²⁻] / [H₂PO₄ ⁻]

taking inverse log function to both sides of this equation:

2.198 = [HPO₄²⁻] / [H₂PO₄ ⁻]

but this is also equivalent to

2.198 = mol HPO₄²⁻ / mol H₂PO₄⁻   (M = mol/V)

We also know that in 1 liter of 0.05 M phosphate, we have 0.05 total mol HPO₄²⁻  and H₂PO₄⁻  , thus

mol HPO₄²⁻ + mol H₂PO₄⁻  = 0.05 mol

2.198 = mol HPO₄²⁻ / mol H₂PO₄⁻  

solving this system of equations calling  x = mol HPO₄²⁻ and y = mol H₂PO₄⁻ , we have:

2.198 = x /y    ⇒ x = 2.198y

x + y = 0.05

2.198y + y = 0.05

3.198 y = 0.05 ⇒ y = 0.05 / 3.198 = 0.016

x = 0.05 - 0.016 = 0.034

and the masses can be calculated from the molar masses ( 141.96 g/mol Na₂HPO₄ and 119.98 g/mol NaH₂PO₄

mol HPO₄²⁻ = 0.034 mol x 141.96 g/mol = 4.827 g

mol H₂PO₄⁻ =  0.016 mol x 119.98 g/mol = 1.920 g

6 0
3 years ago
What is the correct name for Na2CO3
LiRa [457]

Answer:

Sodium carbonate

Explanation:

6 0
3 years ago
Read 2 more answers
Classify each amino acid by the chemical properties of its side chain (R group) at pH 7·Select the amino acid that fits best in
Leno4ka [110]

Answer:

. 1. This amino acid has a positively charged R group: ARGININE

2. This amino acid has a negatively charged R group: ASPARTATE

3. This amino acid has a neutral polar R group: NONE

4. This amino acid has a nonpolar aliphatic R: VALINE

5. This amino acid has an aromatic R group: TRYTOPHAN

Explanation:

1) Arginine contains an extra amino group bearing a positive charge, in its chain which imparts basic properties to it

2) Aspartate contains an extra carboxyl group with a dissociable protron. Once the Protron is dissociated, it carries an extra negative charge in its side chain (R)

3) NONE of the amino acids given belong to this group because amino acids with neutral polar R groups contain functional groups that form hydrogen bonds with water. But, this is not the case with tryptophan aspartate valine or arginine

4) Valine has a R group that is hydrocarbon in nature and thus hydrophobic.

5) Trytophan has a benzene ring in its side chain

7 0
2 years ago
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