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3 years ago

How many atoms are there in each of the following substances?

1 answer:

3 0

To know the number of atoms, it will be necessary to use the formula of avogadro. We calculate the number of moles then we can calculate the number of avogadro.

The molar mass of:

Phosphorus = 31g / mol

Mercury = 200 g / mol

Bismuth = 209 g / mol

Strontium = 87 g / mol.

The number of avogadro (N) is 6.023 10 ^ 23

n = m (mass) / M (molar mass)

number of atoms = n. N = m / M . N

number of phosphorus atoms = 5.14/31 . 6.023 10^23 = 9.98 10 ^ 22 atoms

Number of atoms of mercury = 2.16/200 . 6.023 10^23 = 6.5 10 ^ 21 atoms

Number of bismuth atoms = 1.8/209 . 6.023 10^23 = 5.18 10 ^ 21 atoms

Number of strontium atoms = 8.8 x 10-2 /87 . 6.023 10^23 = 6.09 10 ^ 20 atoms

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3 years ago

Read 2 more answers

An electrochemical cell is composed of pure nickel and pure iron electrodes immersed in solutions of their divalent ions at room

Andrej [43]

Answer:

0.758 V.

Explanation:

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In this case, case when we include the effect of concentration on an electrochemical cell, we need to consider the Nerst equation at 25 °C:

$E=E\°-\frac{0.0591}{n} log(Q)$

Whereas n stands for the number of moles of transferred electrons and Q the reaction quotient relating the concentration of the oxidized species over the concentration of the reduced species. In such a way, we can write the undergoing half-reactions in the cell, considering the iron's one is reversed because it has the most positive standard potential so it tends to reduction:

$Fe^{2+}+2e^-\rightarrow Fe^0\ \ \ E\°=0.440V\\\\Ni^0\rightarrow Ni^{2+}+2e^-\ \ \ E\°=-0.250V$

It means that the concentration of the oxidized species is 0.002 M (that of nickel), that of the reduced species is 0.40 M and there are two moles of transferred electrons; therefore, the generated potential turns out:

$E=(0.440V+0.250V)-\frac{0.0591}{2} log(\frac{0.002M}{0.40M} )\\\\E=0.758V$

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3 years ago

2.5 moles of sodium chloride is dissolved to make 0.050 liters of solution

Hitman42 [59]

The answer is:

the molarity = 50 moles/liters

The explanation:

when the molarity is = the number of moles / volume per liters.

and when the number of moles =2.5 moles

and the volume per liters = 0.05 L

so by substitution:

the molarity = 2.5moles/0.05L

= 50 moles /L

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3 years ago

Conservation of mass was discussed in the background. describe how conservation of mass (actual, not theoretical) could be check

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Conservation of mass can be checked in an experiment . There are three steps to do it in a best way:

1. Weigh all the equipment and materials required in the experiment before the experiment.

2. Avoid spillage and evaporation during the experiment.

3. Weigh all the equipment and materials after the experiment.

If the mass is conserved then weight from step 1 is equal to weight from step 3.

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