The decay of a living things allows chemical elements to be lost.

Alex17521 [72]

Answer:

The physical and chemical properties of the product do not match the properties of the reactant.

Explanation:

Chemical change:

The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.

These changes are irreversible

These changes occur due to chemical reactions

These may not be observed with naked eye

Example:

Combustion of fuel or wood: that oil or wood convert into energy, CO2 and ash in case of wood

Boiling of egg: that change the chemical composition of protein in the egg .

The reaction of Hydrogen and oxygen:

H 2 (g) + O 2 (g) -------------------------------------> 2H 2O (l)

The reaction between sugar and oxygen form a product which is different from the reactant that's why it indicate the occurrence of chemical reaction.

While in case of physical changes just state of matter are changed. Properties remain same.

6 0

2 years ago

How many carbon atoms are represented by the model below<br><br> A) 0<br> B) 3<br> C) 2<br> D) 1

Bogdan [553]

Answer:

Option (B) 3.

Explanation:

In the model represented above, the two extreme represent carbon atoms since no other group are attached to it. The joint at the middle also represent carbon atom.

Thus, we can write a more simplify illustration for the model above as

C—C—C

From the above illustration, we can see that the model contains 3 carbon atom.

5 0

2 years ago

An atom has 11 protons, 10 electrons and 13 neutrons. What is the<br> charge for this atom?

Aliun [14]

Answer:

<h3>the charge is +1 </h3>

Explanation:

<h3>as we know nutral atom have equal number of protons and electrons</h3><h3>from the give this element have 11 protons so if it is nutral it must have 11 electrons,but in the question this atom is charged this means it gains or losts certain amount of electrons , this atom has 11 proton and 10 electron from this we can understand this atom dicreases by 1 from its proton, this means it losts one electron .</h3><h3>when an atom lostes electron it's charge become positive with the number of electrons it lostes .</h3><h3>this atom lost 1 electron there fore it have +1 charge and become ion called cathion</h3>

3 0

2 years ago

Please help, answer questions 3-7

tatyana61 [14]

I don’t know about 3 but I know that 4 is solid, 5 is you’ll feel the vibration first, 6 is you’ll see the lightning first because the speed of light is faster than the speed of sound and 7 is sound waves need a medium to travel and light waves don’t, sound waves are longitudinal and light waves are transverse, and sound waves are mechanical waves while light waves are electromagnetic waves

3 0

3 years ago

A voltaic cell consists of a Pb/Pb2+ half-cell and a Cu/Cu2+ half-cell at 25 ?C. The initial concentrations of Pb2+ and Cu2+ are

VARVARA [1.3K]

Answer:

a) Ecell = 0.5123 V

b) Ecell = 0.4695 V

c) [Pb2 +] = 4.75 M

Explanation:

a)

The reaction at the cathode is represented as follows:

Cu2 + + 2e- -> Cu (s) Eocathode = 0.34 V

The reaction at the anode is equal to:

Pb (s) -> Pb2 + + 2e- Eoanode = -0.13 V

The number of moles of the electrons that are involved is equal to n = 2

Standard cell potential equals Eo = Eocathode - Eoanode = 0.34 V- (-0.13 V) = 0.47 V

The initial cell potential can be calculated with the following formula:

Ecell = Eocell - - 0.0592 / n) log ([(Pb2 +)] / [(Cu2 +)]) = 0.47 - (0.0592 / 2) log (0.052 / 1.4) = 0.5123 V

b)

The reaction in the cell is equal to:

Cu2 + + Pb (s) -> Cu (s) + Pb2 +

The concentration of Cu2 that gives the exercise is equal 0.2 M

Therefore, the change in concentration for Cu2 + is equal to:

Cu2 + = 1.4 M - 0.2 M = 1.2 M

We use the formula from part a)

Ecell = Eocell - (0.0592 / n) log ([(Pb2 +)] / [(Cu2 +)]) = 0.47 - (0.0592 / 2) log (1,252 / 1.2) = 0.4695 V

c)

To find the concentration of Pb2 + when there is a potential change in the cell of 0.37 V, we must clear the concentration of Pb2 + from the following formula:

Eccell = Echocell - (0.0592 / n) log (([Pb2 +]) / ([Cu2 +]))

0.0296 log ([Pb2 +] / [Cu2 +]) = (Eocélula - Ecélula / 0.0296)

Clearing Pb2 +:

[Pb2 +] = 4.75 M

8 0

3 years ago