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AfilCa [17]
3 years ago
14

A certain first-order reaction (A→products) has a rate constant of 9.00×10−3 s−1 at 45 ∘C. How many minutes does it take for the

concentration of the reactant, [A], to drop to 6.25% of the original concentration?
Chemistry
1 answer:
Amiraneli [1.4K]3 years ago
5 0

Answer:

27.8 minutes

Explanation:

The reaction follows a first order

Rate = k[A] = change in concentration/time

k = 9×10^-3s^-1

Let the original concentration of A be y

Concentration of A at time t = 6.25% × y = 0.0625y

Change in concentration = y - 0.0625y = 0.9375y

0.009 × 0.0625y = 0.9375y/t

t = 0.9375y/0.0005625y = 1666.7sec = 1666.7/60 = 27.8 minutes

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Phoenix [80]

The correct answer is option B, that is, hypothesis.  

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6 0
3 years ago
Read 2 more answers
70 points and will give brainliest
ikadub [295]

Answer:

74mL

Explanation:

Given parameters:

Molar mass of citric acid = 192g/mol

Molar mass of baking soda = 84g/mol

Concentration of citric acid  = 0.8M

Mass of baking powder = 15g

Unknown parameters:

Volume of citric acid = ?

Solution

       Equation of the reaction:

            C₆H₈O₇ + 3NaHCO₃ → Na₃C₆H₅O₇ + 3H₂O + 3CO₂

Procedure:

  • We work from the known parameters to the unknown. From the statement of the problem, we can approach the solution from the parameters of the baking powder.
  • From the baking powder, we can establish a molar relationship between the two reactants. We employ the mole concept in this regard.
  • We find the number of moles of the baking powder that went into the reaction using the expression below:

                Number of moles = \frac{mass}{molar mass}

                Number of moles =  \frac{15}{84} = 0.179mole

  • From the equation of the reaction, we can find the number of moles of the citric acid:

             3 moles of baking powder reacted with 1 mole of citric acid

 0.179 moles of baking powder would react with \frac{0.179}{3}:

          This yields 0.059mole of citric acid

  • To find the volume of the citric acid, we use the mole expression below:

    Volume of citric acid = \frac{number of moles}{concentration}

Volume of citric acid = \frac{0.059}{0.8} = 0.074L

Expressing in mL gives 74mL

               

4 0
3 years ago
A person walks north for 5 miles, then south for 8 miles, and then north for 6 more miles. The entire trip takes 8 hours.
Zinaida [17]

Answer:

I am not sure

Explanation:

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2 years ago
Give two reasons why scientists create models to study atoms.
mariarad [96]
IT will be easy to know how chemical reactions occur
It will helps to know the fundamental particles of an atom
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3 years ago
According to the Arrhenius concept, which of the following substances is NOT a base in aqueous solutionsA. NH3B. LiOHC. NaOHD. H
olga_2 [115]

Answer:

NH₃ (Option A)

Explanation:

Arrhenius theory explained that the acids are the ones that have H⁺, either H in its formula. Following this, the bases are the ones that have OH⁻ , either OH and its formula.

It can be used only with compounds with H, or OH.

So the ammonia is not a base, as Arrhenius theory.

It is known that ammonia behaves as a weak base, but it does not have hydroxide ions that can yield to water

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