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alex41 [277]
3 years ago
12

A certain element consists of two stable isotopes. the first has a mass of 68.9 amu and a percent natural abundance of 60.4 %. t

he second has a mass of 70.9 amu and a percent natural abundance of 39.6 %. what is the atomic weight of the element?
Chemistry
1 answer:
Sauron [17]3 years ago
3 0
The average atomic weight of this element can be calculated as follows:
average atomic weight =
(atomic weight of first isotope)(its percentage of abundance) + 
(atomic weight of second isotope)(its percentage of abundance)

atomic weight of first isotope = 68.9 amu
its percentage of abundance = 0.604
atomic weight of second isotope = 70.9 amu
its percentage of abundance = 0.396

So, just substitute in the above equation to get the atomic weight of the element as follows:
atomic weight = (68.9)(0.604) + (70.9)(0.396) = 69.692 amu
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Answer:

<u>STEP I</u>

This is the balanced equation for the given reaction:-

2KOH_{(aq)} + H_2SO_4{}_{(aq)}   \rightarrow K_2SO_4{}_{(aq)} + 2H_2O_{(l)}

<u>STEP II</u>

The compounds marked with (aq) are soluble ionic compounds. They must be

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see, in the equation KOH, H2SO4, and K2SO4 are marked with (aq).

On breaking them into their respective ions :-

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<u>STEP III</u>

Rewriting these in the form of equation

\underline{\pmb{2K^+} }+ 2OH^- + 2H^+ + \pmb{\underline{{SO_4{}^{2-}}} \: \rightarrow \:  \underline{\pmb{2K^+}}} + \underline{\pmb{SO_4{}^{2-}}} + 2H_2O

<u>STEP </u><u>IV</u>

Canceling spectator ions, the ions that appear the same on either side of the equation

<em>(note: in the above step the ions in bold have gotten canceled.)</em>

\boxed{ \mathfrak{ \red{ 2OH^-{}_{(aq)} + 2H^+{(aq.)} \rightarrow H_2O{}_{(l)}}}}

This is the net ionic equation.

____________________________

\\

\mathfrak{\underline{\green{ Why\: KOH \:has\:  been\: taken\: as\: aqueous ?}}}

  • KOH has been taken as aqueous because the question informs us that we have a solution of KOH. by solution it means that KOH has been dissolved in water before use.

[Alkali metal hydroxides are the only halides soluble in water ]

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vovikov84 [41]

Answer:

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Silicon is a 16th group element and it has 4 valance electrons as does the carbon. This is because they both stay in the same group in the periodic table.

Neon is a noble gas which has 8 valance electrons and stays in the 18th group.

Therefore, carbon and silicon have same number of valance electrons which is 4 electrons.

<h3>What are Valence electrons ?</h3>

The electrons in an atom's outermost shell, or energy level, are called valence electrons. For instance, the valence electrons of oxygen are six, with two in the 2s subshell and four in the 2p subshell.

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kirill115 [55]

Answer:

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Explanation:

Correct question

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its vapour dentity is 23. Find the molecular formula

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Solution

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Molecular Weight  is equal to two times the  vapour density

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