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Dahasolnce [82]
3 years ago
14

Is it physical change or chemical change when you smooth a wood chair with sandpaper?

Chemistry
1 answer:
White raven [17]3 years ago
8 0
It should be a chemical change
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The compound methylamine, CH3NH2, is a weak base when dissolved in water. Write the Kb expression for the weak base equilibrium
Veronika [31]

Answer:

Kb = [CH₃NH₃⁺] × [OH⁻] / [CH₃NH₂]

Explanation:

According to Brönsted-Lowry acid-base theory:

  • An acid is a substance that donates H⁺.
  • A base is a substance that accepts H⁺.

When methylamine reacts with water, it behaves as a Brönsted-Lowry base, according to the following reaction.

CH₃NH₂(aq) + H₂O(l) ⇄ CH₃NH₃⁺(aq) + OH⁻(aq)

The basic equilibrium constant (Kb) is:

Kb = [CH₃NH₃⁺] × [OH⁻] / [CH₃NH₂]

3 0
3 years ago
Which one is the least reactive element is<br> Ar<br> Na<br> СІ<br> Mg
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Answer:

Ar

Explanation:

does not react with anything it has a full electron shell so it does not combine and it is a noble gas

7 0
3 years ago
In an experiment, you measure a solution absorbance of 0.2 with a path length of 1cm. If the molar absorptivity coefficient is 5
postnew [5]

A solution has an absorbance of 0.2 with a path length of 1 cm. Given the molar absorptivity coefficient is 59 cm⁻¹ M⁻¹, the molarity is 0.003 M.

<h3>What does Beer-Lambert law state?</h3>

The Beer-Lambert law states that for a given material sample, path length and concentration of the sample are directly proportional to the absorbance of the light.

A solution has an absorbance of 0.2 with a path length of 1 cm. Given the molar absorptivity coefficient is 59 cm⁻¹ M⁻¹, we can calculate the molarity of the solution using the following expression.

A = ε × b × c

c = A / ε × b

c = 0.2 / (59 cm⁻¹ M⁻¹) × 1 cm = 0.003 M

where,

  • A is the absorbance.
  • ε is the path length.
  • b is the molar absorptivity coefficient.
  • c is the molar concentration.

A solution has an absorbance of 0.2 with a path length of 1 cm. Given the molar absorptivity coefficient is 59 cm⁻¹ M⁻¹, the molarity is 0.003 M.

Learn more about the Beer-Lambert law here: brainly.com/question/12975133

7 0
3 years ago
Temperature can weather rocks because A heat can cause minerals to oxidize B. most rocks do not absorb heat evenly C. water cont
Zina [86]

Answer:

c

Explanation:

water contracts when it freezes

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What is the relationship between radius and diameter
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the radius is half the diameter

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