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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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What is the osmolarity of a solution made by dissolving 0.50 mole of the strong electrolyte cacl2 in 1.0 l of solution?
valina [46]
Osmolarity=osmole  of  the  solute/litres  of  the  solution
ionic  equation  for  dissociation  of  CaCl2  is
CaCl2--->Ca2+   +2Cl-
total osmoles  for  reaction are    1(Ca2+)  + 2(Cl-)= 3 osmoles
therefore
 
0.50 moles of  CaCl2  x 3 osmoles/ 1mole of  CaCl2 = 1.5osmoles
osmolarity=1.5 /1.0  L=1.5 osmol/l
6 0
3 years ago
What is the change in internal energy (ΔΕ) of a system when 5 kJ of work is done on the system while it releases 13 kJ of energy
meriva

The change in internal energy (ΔΕ) of a system : -8 kJ

<h3>Further explanation  </h3>

The laws of thermodynamics 1 state that: energy can be changed but cannot be destroyed or created  

The equation is:  

 \tt \Delta U=Q+W

Energy owned by the system is expressed as internal energy (U)  

This internal energy can change if it absorbs heat Q (U> 0), or releases heat (U <0). Or the internal energy can change if the system does work or accepts work (W)  

The sign rules for heat and work are set as follows:  

• The system receives heat, Q +  

• The system releases heat, Q -  

• The system does work, W -  

• the system accepts work, W +  

5 kJ of work is done on the system : W = +5 kJ

releases 13 kJ of energy to the surroundings : Q = -13 kJ

\tt \Delta E=-13+5=-8~kJ

6 0
3 years ago
What happens to molecules when a substance is cooled?​
marissa [1.9K]

Answer:

causes a substance to change from a liquid to a solid.

Explanation:

3 0
3 years ago
Read 2 more answers
The iron content of foods can be determined by dissolving them in acid (forming Fe3+), reducing the iron(III) to iron(II), and t
____ [38]

Answer:

  • <em>Oxidation half-reaction</em>:

Fe²⁺(aq) →  Fe³⁺(aq) + 1e⁻

  • <em>Reduction half-reaction</em>:

Ce⁴⁺(aq) + 1e⁻ →  Ce³⁺(aq)

Explanation:

The reaction that takes place is:

  • Fe²⁺(aq) + Ce⁴⁺(aq) → Fe³⁺(aq) + Ce³⁺(aq)

The <em>oxidation half-reaction</em> is:

  • Fe²⁺(aq) →  Fe³⁺(aq) + 1e⁻

It is an oxidation because the oxidation state of Fe increases from 2+ to 3+.

The <em>reduction half-reaction</em> is:

  • Ce⁴⁺(aq) + 1e⁻ →  Ce³⁺(aq)

It is a reduction because the oxidation state of Ce decreases from 4+ to 3+.

4 0
3 years ago
Imagine you pour some hot soup into a bowl. You place your hands on the outside of the bowl and feel that the bowl is very warm.
yuradex [85]

Um because of the energy in the heat? XD idk

5 0
3 years ago
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