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2 years ago

Whats the pure substance that cannot be separated into any other substances

2 answers:

8 0

A pure substance that cannot be separated into simpler substances by physical or chemical means. A pure substance composed of two or more elements that are chemically combined.

ryzh [129]2 years ago

8 0

An element is a pure substance that cannot be separated into any other substances.

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Naturally occurring element X exists in three isotopic forms: X-28 (27.979 amu, 92.21% abundance), X-29 (28.976 amu 4.70% abunda

bezimeni [28]

Answer: The average atomic mass of X is 28.09 amu

Explanation:

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

$\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$ .....(1)

For isotope 1:

Mass of isotope 1 = 27.979 amu

Percentage abundance of isotope 1 = 92.21 %

Fractional abundance of isotope 1 = 0.9212

For isotope 2:

Mass of isotope 2 = 28.976 amu

Percentage abundance of isotope 2 = 4.70 %

Fractional abundance of isotope 2 = 0.0470

For isotope 3:

Mass of isotope 3 = 29.974 amu

Percentage abundance of isotope 3 = 3.09 %

Fractional abundance of isotope 3 = 0.0309

Putting values in equation 1, we get:

$\text{Average atomic mass of X}=[(27.979\times 0.9212)+(28.976\times 0.0470)+(29.974\times 0.0309)]$

$\text{Average atomic mass of X}=28.09amu$

Hence, the average atomic mass of X is 28.09 amu

4 0

3 years ago

Which of the following are weak electrolytes in aqueous solutions? Select ALL that apply.

Mandarinka [93]

Answer:

Weak electrolytes are

HgCl2 and NH₃

Explanation:

Electrolytes are compounds that conduct electricity while in molten or aqueous form.
Electrolytes may therefore be decomposed by passing electric current through them.

They may be either strong or weak electrolytes.

Strong electrolytes are those that ionize completely to form mobile ions while weak electrolytes ionize partially to generate ions.

Examples of weak electrolytes are HgCl2, NH₃
Examples of strong electrolytes are LiOH, HClO₄, and HI.

3 0

2 years ago

What are possible reasons for a percent yield that is under 100%

matrenka [14]

Answer:

Percentage Yield is given as,

%age Yield = Actual Yield / Theoretical Yield × 100

This shows that the %age yield is directly depending upon the actual yield. And most of the time the percentage yield is less than 100 % because of the following factors.

Impure Starting Materials:

If the starting materials (reactants) are not pure then reaction will not completely form the desired product. Different by products will form which will decrease the %age yield.

Incomplete Reactions:

Not all reactions go to completion. In many reactions the starting material after some time stops forming the product due to different conditions. Some reactions attain equilibrium and stop increasing the amount of product. While, in some reactions a by products (like water) formed often react with the product to give a reverse reactions. Hence, the chemistry of reactions also causes the decrease in %age yield.

Handling:

Another major reason for decrease in yield is handling the product. Always some of the product is lost during the workup of the reaction like, taking TLC, doing solvent extraction, doing column chromatography, taking characterization spectrums. So, we can conclude that the %age yield will always be less than 100%.

5 0

3 years ago

Please give me solved answer pic its really importen

inn [45]

Where’s the picture?

5 0

2 years ago

SOMEONE HELP PLEASE 60 POINTS!!!!!!! IM TIMED TOO SO PLS

Sergeu [11.5K]

Explanation:

ooohhhh it's free points,,,thank you mwahhh hahahahahaha jokeee

sorry I don't have any ideas

4 0

2 years ago