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mafiozo [28]
3 years ago
9

Trevor dissolves sodium hydroxide pellets in a beaker of water at room temperature, and notes that the beaker becomes warm. Whic

h correctly designates the signs of ΔH, ΔS, and ΔG for this process?
A. ΔH > 0, ΔS > 0, and ΔG < 0
B. ΔH < 0, ΔS > 0, and ΔG < 0
C. ΔH > 0, ΔS > 0, and ΔG > 0
D. ΔH < 0, ΔS < 0, and ΔG > 0
Chemistry
2 answers:
Ainat [17]3 years ago
8 0
Alright, so this question covers the subject of spontaneous reactions. Reactions tend to be spontaneous if the products have a lower potential energy than the reactants or when the product molecules are less ordered than the reactant molecules. This may seem a little confusing but to put it simply, spontaneous reactions occur naturally. 
This means there is no external force for the reaction, usually exothermic, and increases entropy. Gibbs free energy change helps us determine if the reaction is spontaneous:

   delta G= delta H -T(delta S)       spontaneous if delta G<0

Remember that H stands for enthalpy, or potential energy; T is for temperature; and S is entropy, the amount of disorder(spontaneous reactions increase in entropy take for ice to liquid water).

- delta H= exothermic  
The reaction in the problem releases heat so the enthalpy is negative.

delta S increases with increased temperature
The entropy will be positive.

Plugging this in the Gibbs equation, you can assume delta G will be less than 0.

Therefore, the answer is B. Sorry for the long and possibly not helpful explanation. I'm learning this material currently myself. Best of luck!


andreyandreev [35.5K]3 years ago
3 0

Answer: B. ΔH < 0, ΔS > 0, and ΔG < 0

Explanation:

As the beaker gets warm ,the energy has been released when Trevor dissolves sodium hydroxide pellets in a beaker of water. Thus as the energy has been released in the reaction, the reaction is exothermic and the change in enthalpy i.e. \DeltaH is negative and is less than zero.

The entropy is the measure of degree of randomness. The entropy increases when the randomness increases and the entropy decreases when the randomness decreases. When a substance dissolves in water, it dissociate into ions and hence the randomness increases thus the change in entropy i.e. \DeltaS is positive and  is more than zero.

also \Delta G=\Delta H-T\Delta S

\Delta G=(-ve)-T(+ve)=(-ve)(-ve)=-ve

That is change in gibbs free energy i.e. \Delta G is negative and is less than zero.

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Aluminum metal reacts with aqueous cobalt(II) nitrate to form aqueous aluminum nitrate and cobalt metal. What is the stoichiomet
Lelu [443]

Answer:

the stoichiometric coefficient for cobalt is 3

Explanation:

the unbalanced reaction would be

Co(NO₃)₂+ Al → Al(NO₃)₃ + Co

One way to solve is to build a system of linear equations for each element (or group as NO₃) , knowing that the number of atoms of each element is conserved.

For smaller reactions a quick way to solve it can be:

- First the Co as product and as reactant needs to have the same stoichiometric coefficient

- Then the Al as product and as reactant needs to have the same stoichiometric coefficient

- After that we look at the nitrates . There are 2 as reactants and 3 as products . Since the common multiple is 6 then multiply the reactant by 3 and the product by 2.

Finally the balanced equation will be

3 Co(NO₃)₂+ 2 Al → 2 Al(NO₃)₃ + 3 Co

then the stoichiometric coefficient for cobalt is 3

7 0
3 years ago
A sample of 87.6 g of carbon is reacted with 136 g of
Vadim26 [7]

Answer:

A. fluorine, 1.79 moles

Explanation:

Given parameters:

Mass of carbon  = 87.7g

Mass of fluorine gas  = 136g

Unknown:

The limiting reactant and the maximum amount of moles of carbon tetrafluoride that can be produced  = ?

Solution:

   Equation of the reaction:

             C    +   2F₂ →   CF₄  

let us find the number of the moles the given species;

  Number of moles = \frac{mass}{molar mass}  

  C;   molar mass = 12;

            Number of moles  = \frac{87.7}{12}   = 7.31moles

 F;  molar mass  = 2(19)  = 38g/mol

             Number of moles  = \frac{136}{38}   = 3.58moles

 So;

   From the give reaction:

          1 mole of C requires 2 moles of F₂

         7.31 moles of C will then require 2 x 7.31 moles of F₂ = 14.62moles

But we have 3.58 moles of the F₂;

  Therefore, the reactant in short supply is F₂ and it is the limiting reactant;

 So;

       2 moles of F₂ will produce  mole of CF₄  

       3.58 moles of F₂ will then produce \frac{3.58}{2}  = 1.79moles of CF₄

6 0
3 years ago
Which best describes the act of using senses or tools to gather information? creating a hypothesis making an observation summari
MAXImum [283]

Answer:

making an observation

Explanation:

its the right answer

3 0
3 years ago
First, get about 20 mL of the quinine stock solution in a clean beaker to prepare 250 mL of about 2 ppm quinine in 0.05 M H2SO4.
iris [78.8K]

Answer:

Volume of acid, Va=250mL; Volume of quinine,Vb=20mL; Molarity of acid, Ma=0.05M.

Molar mass of acid= H2+S+O4= 2+32+(16X4)= 2+32+64=98g

Concentration of acid, Ca= Molar mass of acid/ Ma =98/0.05=1960g/mol

Explanation: To calculate concentration of quinine, Cb is as follow

Va*Ca=Vb*Cb

∴ Cb=Va*Ca/Vb =250*1960/20 =24500g/mol

5 0
3 years ago
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jek_recluse [69]
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