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2 years ago

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

$\\ \tt\rightarrowtail pH+pOH=14$

$\\ \tt\rightarrowtail pOH=14-4.95$

$\\ \tt\rightarrowtail pOH=9.05$

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

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

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

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

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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

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3 years ago

Which chemical reaction needs more energy to break bonds in the reactants

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Answer:An endothermic reaction

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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>Getting to the equation:</h3>

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

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

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

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

Looking into the equation more carefully, we see:

1 atom of Calcium reacts with 2 molecules of water to give 1 molecule of Calcium Hydroxide alongwith 1 molecule of Hydrogen gas.

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

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

Mass of one atom of Calcium = it's gram atomic mass

= 40 g

Mass of one "molecule" of Hydrogen

= 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 (during the particular reaction)

=> 40g of Calcium gives = 2g of Hydrogen

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

= $\frac{1}{20}$ g Hydrogen

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

<h3>Answer:</h3>

We're provided with 20g of Calcium,

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

= 1 g H2

_______________

Hope this helps!

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2 years ago

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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

A large piece of jewelry has a mass of 132.6 g. a graduated cylinder initially contains 48.6 ml water. when the jewelry is subme

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

Solution:- Mass of jewelry is given as 132.6 g. Initial volume of water in the graduated cylinder is 48.6 mL and the volume becomes 61.2 mL when this jewelry is submerged in the cylinder.

So, the volume of the jewelry = 61.2 mL - 48.6mL = 12.6 mL

We know that, $density=\frac{mass}{volume}$

Let's plug in the values in the above formula to calculate the density:

$density=\frac{132.6g}{12.6mL}$

$density=10.5\frac{g}{mL}$

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.

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3 years ago