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Evgen [1.6K]
2 years ago
9

The H⁺ concentration in an aqueous solution at 25 °C is 9.1 × 10⁻⁴. What is [OH⁻]?

Chemistry
1 answer:
Vinvika [58]2 years ago
5 0

Steps:-

  • First we calculate pH then pOH then [OH-]

\\ \tt\rightarrowtail pH=-log[H^+]

\\ \tt\rightarrowtail pH=-log[9.1\times 10^{-4}]

\\ \tt\rightarrowtail pH=-log9.1-log10^{-4})

\\ \tt\rightarrowtail pH=0.95+4

\\ \tt\rightarrowtail pH=4.95

Now

\\ \tt\rightarrowtail pH+pOH=14

\\ \tt\rightarrowtail pOH=14-4.95

\\ \tt\rightarrowtail pOH=9.05

So

\\ \tt\rightarrowtail -log[OH^-]=9.05

\\ \tt\rightarrowtail log[OH^-]=-9.05

\\ \tt\rightarrowtail OH^-=10^{-9.05}

\\ \tt\rightarrowtail OH^-=8.91\times 10^{-4}

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Salsk061 [2.6K]

Answer:

The answer is 1.61 × 10²³ atoms

Explanation:

To determine number of atoms, we will use the formula below

Number of atoms = number of moles (n) × avogadro's constant (6.02 x 10²³)

n was not provided, hence we will solve for n

n = mass/ molar mass

molar mass of carbon monoxide, CO (where C is 12 and O is 16) is 12 + 16 = 28

mass was provided in the question as 7.48

n = 7.48/28

n = 0.267

Hence,

number of atoms = 0.267 × 6.02 x 10²³

= 1.61 × 10²³ atoms

3 0
3 years ago
Which chemical reaction needs more energy to break bonds in the reactants
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Answer:An endothermic reaction

Explanation: In an endothermic reaction, it takes more energy to break the bonds of the reactants than is released when the bonds in the products are formed. In an endothermic reaction, the temperature goes down.

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3 years ago
Read 2 more answers
Read that From picture and tell me the answer please​
Dafna11 [192]

Answer:

1g Hydrogen

Explanation:

<h3><u>Getting</u><u> </u><u>to</u><u> </u><u>the</u><u> </u><u>equation</u><u>:</u></h3>

Calcium in water reacts vigorously to give a cloudy white <em>Precipitate</em><em> </em>(compound) called Calcium hydroxide alongwith the evolution of Hydrogen gas.

\boxed{ \mathsf{Ca + H_2O \rightarrow Ca(OH)_2 + H_2}}

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

<h3><u>Balancing</u><u> </u><u>the</u><u> </u><u>equation</u><u>:</u><u> </u></h3>

This reaction is not in it's balanced form! The number of atoms of Hydrogen on the left is 2 while that on the right is 4,I.e.,they're not equal.

Adding a 2 in front of H2O solves the problem by making the number of atoms of each element on both the sides equal.

\mathsf{Ca +2 H_2O \rightarrow Ca(OH)_2 + H_2}

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

<h3><u>Observations</u><u>:</u></h3>

Looking into the equation more carefully, we see:

<u><em>1</em><em> </em></u><em>atom</em><em> </em><em>of</em><em> </em><em>Calcium</em><em> </em><em>reacts</em><em> </em><em>with</em><em> </em><em><u>2</u></em><em> </em><em>molecules</em><em> </em><em>of</em><em> </em><em>water</em><em> </em><em>to</em><em> </em><em>give</em><em> </em><u><em>1</em><em> </em></u><em>molecule</em><em> </em><em>of</em><em> </em><em>Calcium</em><em> </em><em>Hydroxide</em><em> </em><em>alongwith</em><em> </em><em><u>1</u></em><em> </em><em>molecule</em><em> </em><em>of</em><em> </em><em>Hydrogen</em><em> </em><em>gas</em><em>.</em>

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

<h3><u>Gram</u><u> </u><u>atomic</u><u> </u><u>and</u><u> </u><u>molecular</u><u> </u><u>masses</u><u> </u></h3>

<u>Mass</u><u> </u><u>of</u><u> </u><u>one</u><u> </u><u>atom</u><u> </u><u>of</u><u> </u><u>Calcium</u><u> </u>= it's gram atomic mass

= 40 g

<u>Mass of one "molecule" of Hydrogen</u>

= it's Gram molecular mass

= gram mass of one atom × number of atoms in one molecule

= 1 × 2

= 2 g

So,

according to our observation:

One atoms of Calcium gives one molecule of Hydrogen <em>(during the particular reaction)</em>

=><u> 40g of Calcium gives = 2g of Hydrogen</u>

•°• 1 g of Calcium gives = \frac{2}{40}

= \frac{1}{20} g Hydrogen

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

<h3><u>Answer</u><u>:</u></h3>

We're provided with 20g of Calcium,

=> 20g of Calcium gives = 20 × \frac{1}{20} g H2

<u>= 1 g H2</u>

_______________

Hope this helps!

6 0
2 years ago
Disadvantages of Mendeleev's periodic table​
mestny [16]

Answer:

Various limitations of Mendeleev's periodic table are:-

Position of hydrogen - he couldn't assign a correct position to hydrogen as it showed properties of both alkali and halogens .

Position of isotopes - he considered that the properties of elements are a function of their atomic masses. Hence isotopes of a same element couldn't be placed.

In the d-block , elements with lower atomic number were placed before higher atomic number.

Explanation:

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3 years ago
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Answer:- Density is 10.5 grams per mL and the substance is Silver(Ag).

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So, the density of the jewelry is 10.5\frac{g}{mL} .

The substance from which the jewelry is made could easily be identified by comparing the calculated density with the density values given for different substances in the density table.

Looking at the density table, 10.5 grams per mL is the density for silver. So, the jewelry is made up from Silver.

4 0
3 years ago
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