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12345 [234]
3 years ago
11

Alchemists were medieval scholars and philosophers who were the forerunners of modern-day chemists. many tried repeatedly to tra

nsform lead (atomic number 82) into gold (atomic number 79). explain why they never did succeed.
Chemistry
1 answer:
AlladinOne [14]3 years ago
8 0

Answer is: because they were using simple chemical reactions to transform elements, but that is possible only with nuclear reactions, which in that time were not possible to conduct.

Nuclear reactions can produce new elements, because number of protons and neutrons is changed, lead and gold have different atomic and mass numbers.

The electrons of an atom participates in a chemical reaction, chemical reactions involve the rearrangement of electrons, because there is transfer, loss, gain and sharing of electrons in chemical reactions, new elements are not formed.


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Two students made the Lewis dot diagrams of H2O. The diagrams are as shown.
netineya [11]

Answer:

Only student A

Explanation:

don’t worry I got a 100

7 0
3 years ago
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Match each element to the number of electrons in its valence shell.
irinina [24]

Answer:

C: 4

H: 1

Mg: 2

O : 6

Explanation:

You can quickly find out the number of valence electrons by looking at where the element is on the periodic table and referring to the table that is attached.

6 0
10 months ago
Helllpppp!!!!!! Please
pav-90 [236]

Answer: (C) Statements (i) and (iii)

Explanation: According to byjus.com, group VII elements are known as Halogens.

Not only that, but bbc.co.uk says " Atoms of group 7 elements all have seven electrons in their outer shell. This means that the halogens all have similar chemical reactions ."

It may just be (b) though as these are chemical reactions.

3 0
2 years ago
100 POINTS PLEASE HELP!! Honors Stoichiometry Activity Worksheet Instructions: In this laboratory activity, you will taste test
Shtirlitz [24]

Answer:

2 water + sugar + lemon juice → 4 lemonade

Moles of water present in 946.36 g of water=\frac{946.36 g}{236.59 g/mol}=4 mol=

236.59g/mol

946.36g

=4mol

Moles of sugar present in 196.86 g of water=\frac{196.86 g}{225 g/mol}=0.8749 mol=

225g/mol

196.86g

=0.8749mol

Moles of lemon juice present in 193.37 g of water=\frac{193.37 g}{257.83 g/mol}=0.7499 mol=

257.83g/mol

193.37g

=0.7499mol

Moles of lemonade in 2050.25 g of water=\frac{2050.25 g}{719.42 g/mol}=2.8498 mol=

719.42g/mol

2050.25g

=2.8498mol

As we can see that number of moles of lemon juice are limited.

So, we will consider the reaction will complete in accordance with moles of lemon juice.

1 mole lemon juice reacts with 2 mol of water,then 0.7499 mol of lemon juice will react with:

\frac{2}{1}\times 0.7499 mol = 1.4998 mol

1

2

×0.7499mol=1.4998mol of water

Mass of water used = 1.4998 mol × 236.59 g/mol=354.8376 g

Water remained unused = 946.36 g - 354.8376 g =591.5223 g

1 mole lemon juice reacts with mol of sugar,then 0.7499 mol of lemon juice will react with:

\frac{1}{1}\times 0.7499 mol = 0.7499 mol

1

1

×0.7499mol=0.7499mol of water

Mass of sugar used = 0.7499 mol × 225 g/mol = 168.7275 g

Sugar remained unused = 196.86 g - 28.1325 g

1 mole of lemon juice gives 4 moles of lemonade.

Then 0.7499 mol of lemon juice will give:

\frac{4}{1}\times 0.7499 mol=2.996 mol

1

4

×0.7499mol=2.996mol of lemonade

Mass of lemonade obtained = 2.996 mol × 719.42 g/mol = 2157.9722 g

Theoretical yield of lemonade = 2157.9722 g

Experimental yield of lemonade = 2050.25 g

Percentage yield of lemonade:

\frac{\text{Experimental yield}}{\text{theoretical yield}}\times 100

theoretical yield

Experimental yield

×100

\frac{2050.25 g}{2157.9722 g}\times 100=95.00\%

2157.9722g

2050.25g

×100=95.00%

6 0
3 years ago
Read 2 more answers
How can you distinguish between crystalline allotropic modifications of Sulphur from those of amorphous allotrops?​
Burka [1]

The crystalline allotropes of sulfur are very strong and have a high melting and boiling point while the amorphous allotropes of sulfur are brittle and breaks easily.

<h3>What is a crystalline substance?</h3>

A crystalline substance is one that has a definite arrangement of the atoms in the substance. An amorphous substance lacks this definite arrangement. We can see this arrangement when we conduct an X-ray crystallography of the sulfur.

Also, the crystalline allotropes of sulfur are very strong and have a high melting and boiling point while the amorphous allotropes of sulfur are brittle and breaks easily.

Learn more about sulfur:brainly.com/question/13469437

#SPJ1

4 0
1 year ago
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