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3 years ago

As matter changes, what happens to the energy?

Chemistry

1 answer:

OlgaM077 [116]3 years ago

4 0

Energy, Temperature, and Changes of State

Matter either loses or absorbs energy when it changes from one state to another. For example, when matter changes from a liquid to a solid, it loses energy. The opposite happens when matter changes from a solid to a liquid.

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How many grams of water are produced when 4.50 L of

MA_775_DIABLO [31]

The answer for the following problem has been mentioned below.

Therefore the mass of the water is 5.802 grams.

Explanation:

Given:

volume of oxygen (V) = 4.50 L

Temperature (T) = 425 K

pressure of oxygen (P) = 2.50 atm

Gram molecular mass of oxygen (M) = 16.0 grams

To calculate:

mass of water (m)

We know;

According to the ideal gas equation;

P × V = n × R × T

As we know;

no of moles = $\frac{m}{M}$

m represents the mass of oxygen (m)

M represents the Gram molecular mass (M)

According to above mentioned equation;

P × V = n × R × T

P represents the pressure of the oxygen

V represents the volume of the oxygen

n represents the no of moles of the oxygen

R represents the universal gas constant

where,

the value of R is 0.0821 L atm/K moles

Substituting the values in the above equation;

2.50 × 4.50 = $\frac{m}{16.0}$ × 0.0821 × 425

11.25 = $\frac{m}{16.0}$ × 34.8925

180 = m × 34.8925

m = $\frac{180}{34.8925}$

m = 5.158 grams

Therefore the mass of the of oxygen is 5.158 grams

Now;

As we know;

$\frac{m_{1} }{M_{1} } = \frac{m_{2} }{M_{2} }$

where;

$m_{1}$ represents the mass of the oxygen

$M_{1}$ represents the gram molecular mass of the oxygen

$m_{2}$ represents the mass of the water

$M_{2}$ represents the gram molecular mass of water

From the above given formula,

$\frac{5.158}{16.0}$ = $\frac{m_{2} }{18}$

where;

Gram molecular weight of water = 18.0 u

$m_{2}$ = 5.802 grams

Therefore the mass of the water is 5.802 grams.

5 0

3 years ago

The standard cell potential Ec for the reduction of silver ions with elemental copper is 0.46V at 25 degrees celsius. calculate

Cloud [144]

Answer : The $\Delta G$ for this reaction is, -88780 J/mole.

Solution :

The balanced cell reaction will be,

$Cu(s)+2Ag^+(aq)\rightarrow Cu^{2+}(aq)+2Ag(s)$

Here, magnesium (Cu) undergoes oxidation by loss of electrons, thus act as anode. silver (Ag) undergoes reduction by gain of electrons and thus act as cathode.

The half oxidation-reduction reaction will be :

Oxidation : $Cu\rightarrow Cu^{2+}+2e^-$

Reduction : $2Ag^++2e^-\rightarrow 2Ag$

Now we have to calculate the Gibbs free energy.

Formula used :

$\Delta G^o=-nFE^o$

where,

$\Delta G^o$ = Gibbs free energy = ?

n = number of electrons to balance the reaction = 2

F = Faraday constant = 96500 C/mole

$E^o$ = standard e.m.f of cell = 0.46 V

Now put all the given values in this formula, we get the Gibbs free energy.

$\Delta G^o=-(2\times 96500\times 0.46)=-88780J/mole$

Therefore, the $\Delta G$ for this reaction is, -88780 J/mole.

7 0

3 years ago

Which of the following has a melting point greater than room temperature?

nikdorinn [45]

Technically, the answer is iron. Oxygen has a melting point way below zero (-219 degrees celsius), ice becomes water AT room temperature and bromine is already a liquid at room temperature. So, iron has a melting point greater than room temperature due to the fact that metals are made up of giant structures of atoms in a regular arrangement, and there are strong forces of electrostatic attraction between positive metal ions and negative electrons, meaning that a lot of heat energy is required to break the bonds, i.e. a very high melting point, approx. 1500 degrees celsius. Hope this helps.

6 0

3 years ago

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Who's your celebrity crush and why?

dezoksy [38]

Answer:

Ian Somerhalder because he's JUST SO fine

Explanation:

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3 years ago

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