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Rina8888 [55]
3 years ago
8

The molar mass of a solid carboxylic acid is determined by titrating a known mass of the acid with a standardized solution of Na

OH to a phenolphthalein endpoint. Which errors will lead to a molar mass that is smaller than the actual molar mass? I. Some of the acid is spilled when being transferred into the titration flask. II.The endpoint is recorded when the solution is dark red in color rather than light pink.
Chemistry
1 answer:
laiz [17]3 years ago
8 0

The answer is: II.The endpoint is recorded when the solution is dark red in color rather than light pink.

The endpoint is the point at which the indicator changes colour in a colourimetric titration and that is point when titration must stop.  

Phenolphthalein is colorless in acidic solutions and pink in basic solutions. If  this indicator change color to dark red, more base is added and endpoint is not accurate.

If the the acid is spilled before titration, that does not make endpoint wrong and molar mass can be calculated.

In this example we can take acetic acid as carboxylic acid; basic salt sodium acetate CH₃COONa is formed from the reaction between weak acid (in this example acetic acid CH₃COOH) and strong base (in this example sodium acetate NaOH).  

Balanced chemical reaction of acetic acid and sodium hydroxide:  

CH₃COOH(aq) + NaOH(aq) → CH₃COONa(aq) + H₂O(l).  

Neutralization is is reaction in which an acid (in this example vinegar or acetic acid CH₃COOH) and a base react quantitatively with each other.

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The sign of the entropy change, ΔS, for the following processes include:

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What is Entropy?

This is referred to the degree of randomness or disorderliness of a system and is denoted as S.

Entropy change is usually positive when solid or liquid reactant is converted into gas product and vice versa.

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6 0
2 years ago
Aqueous sulfuric acid (H2SO4) reacts with solid sodium hydroxide (NaOH) to produce aqeous sodium sulfate (Na2SO4) and liquid wat
Montano1993 [528]

Answer:

The theoretical yield of water formed is 2.2 grams

Explanation:

Step 1: Data given

Mass of H2SO4 = 5.9 grams

Mass of NaOH = 6.6 grams

Molar mass H2SO4 = 98.08 g/mol

Molar mass of NaOH = 40.0 g/mol

Step 2: The balanced equation

2NaOH + H2SO4 → Na2SO4 + 2H2O

Step 3: Calculate moles

Moles = mass / molar mass

Moles H2SO4 = 5.9 grams / 98.08 g/mol

Moles H2SO4 = 0.060 moles

Moles NaOH = 6.6 grams / 40.0 g/mol

Moles NaOH = 0.165 moles

Step 4: Calculate the limiting reactant

For 2 moles NaOH we need 1 mol H2SO4 to produce 1 mol Na2SO4 and 2 moles H2O

H2SO4 is the limiting reactant. It will completely be consumed ( 0.060 moles). NaOH is in excess . There will react 2*0.060 = 0.120 moles

There will remain 0.165 - 0.120 = 0.045 moles NaOH

Step 5: Calculate moles H2O

For 2 moles NaOH we need 1 mol H2SO4 to produce 1 mol Na2SO4 and 2 moles H2O

For 0.0600 moles H2SO4 we'll have 2*0.0600 = 0.120 moles H2O

Step 6: Calculate mass H2O

Mass H2O = 0.120 moles * 18.02 g/mol

Mass H2O = 2.16 grams

The theoretical yield of water formed is 2.2 grams

4 0
3 years ago
Why is sulfuric acid considered a bronsted acid?
elena-14-01-66 [18.8K]
Sulfuric acid is considered as a Bronsted acid because it is a proton donor. When in solution, the molecules of the compound dissociates into ions, the hydrogen ion and the the sulfate ion. It donates the hydrogen ion so it is an acid, a bronsted acid.
4 0
3 years ago
What are atoms of an element with different numbers of neurons called?
uysha [10]
<span>The atoms of a chemical element can exist in different types. These are calledisotopes. They have the same number of protons (and electrons), but different numbers of neutrons.</span>
5 0
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Refer to the reaction between magnesium and oxygen In the introduction. What elements is oxidizing?write the oxidation number fo
erica [24]

Answer:

Oxidizing element: Mg

Explanation:

Reaction of magnesium and oxygen can be written as:

2Mg +O_2 \rightarrow 2MgO

while writting chemical reaction between two atom or element then write their natural form i.e. how that atom or element exist in the nature.

eg. reaction of any element with Oxygen atom then we can not write directly O because oxygen exist in the nature in form of O_2

finding oxidation number each side:

Reactant side:

Mg=0;

O=0;

product side:

Mg=+2;

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from above:

oxidation number of Mg is increasing hence this is oxidizing element

7 0
3 years ago
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