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4 years ago

What happens to energy when matter undergoes a chemical or physical change?

Chemistry

1 answer:

alexdok [17]4 years ago

8 0

Chemical- The atoms that make the current substance are rearranged into new substances.

Physical- during a physical change, nothing new is created.

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Can a mini fridge still be used if you break the freezer

Romashka [77]

The fridge part can, just not the freezer, I think.

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4 years ago

Planets X and Y orbit each other in space. Which changes would have the greatest effect on increasing the gravitational attracti

liubo4ka [24]

Answer:

halving, the mass of planet X and halving the distance between the planets

3 0

3 years ago

Calculate the equilibrium constant for the following reaction: Co2+ (aq) + Zn(s> CO (s) + Zn2+ (aq)

Simora [160]

Answer: The $K_{eq}$ of the reaction is $1.73\times 10^{16}$

Explanation:

For the given half reactions:

Oxidation half reaction: $Zn(s)\rightarrow Zn^{2+}+2e^-;E^o_{Zn^{2+}/Zn}=-0.76V$

Reduction half reaction: $Co^{2+}+2e^-\rightarrow Co(s);E^o_{Co^{2+}/Co}=-0.28V$

Net reaction: $Zn(s)+Co^{2+}\rightarrow Zn^{2+}+Co(s)$

Oxidation reaction occurs at anode and reduction reaction occurs at cathode.

To calculate the $E^o_{cell}$ of the reaction, we use the equation:

$E^o_{cell}=E^o_{cathode}-E^o_{anode}$

Putting values in above equation, we get:

$E^o_{cell}=-0.28-(-0.76)=0.48V$

To calculate equilibrium constant, we use the relation between Gibbs free energy, which is:

$\Delta G^o=-nfE^o_{cell}$

and,

$\Delta G^o=-RT\ln K_{eq}$

Equating these two equations, we get:

$nfE^o_{cell}=RT\ln K_{eq}$

where,

n = number of electrons transferred = 2

F = Faraday's constant = 96500 C

$E^o_{cell}$ = standard electrode potential of the cell = 0.48 V

R = Gas constant = 8.314 J/K.mol

T = temperature of the reaction = $25^oC=[273+25]=298K$

$K_{eq}$ = equilibrium constant of the reaction = ?

Putting values in above equation, we get:

$2\times 96500\times 0.48=8.314\times 298\times \ln K_{eq}\\\\K_{eq}=1.73\times 10^{16}$

Hence, the $K_{eq}$ of the reaction is $1.73\times 10^{16}$

8 0

3 years ago

Show your work and include answer with units. How many atoms in 55 grams of magnesium

Georgia [21]

Answer:

1.38 x $10^{24}$ atoms

Explanation:

To get grams to atoms/molecules/particles we need to first convert grams > moles > atoms. This also applies in the other direction, where you have moles as that stepping stone.

Some key information we need:

Magnesium's molar mass= 24g/mol

Avogadro's Number= 6.022 x $10^{23}$ atoms

Where there is 1 mol per 6.022 x $10^{23}$ atoms

*This maybe be something you want to memorize.

Grams to moles using molar mass , then to atoms using avogadro's number.

55g Mg x $\frac{1 mol}{24g/mol}$ x $\frac{6.022 x 10^{23} atoms }{1 mol}$ = 1.38 x $10^{24}$ atoms

8 0

3 years ago

All amino acids contain which of the following groups

anzhelika [568]

Answer:

Explanation:

Amino acid functional groups refer to the amino (~NH3+) and carboxyl (~COOH) group bonded to the alpha carbon. At biological pH (~7.2) the carboxyl will become deprotonated to carboxylate (~COO-). Each amino acid also has a side chain (R group) that may also exhibit functionality.Aug 4, 2015

6 0

3 years ago