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bixtya [17]
3 years ago
8

g When considering the effects of temperature on spontaneity, if both ΔH and ΔS are positive, _______. Select the correct answer

below: the process is spontaneous at all temperatures
Chemistry
1 answer:
Margaret [11]3 years ago
6 0

Explanation:

The spontaneity of a system is deduced by the sign of the gibbs free energy value. If it is negative, it means the process / reaction is spontaneous however a positive value indicates the such process is not spontaneous.

Gibbs free energy, enthalpy and entropy are related by the following equation;

ΔG = ΔH - TΔS

A positive value of enthalpy, H and entropy, S means that G would always be a negative value at all temperatures.

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What would happen when a substance changes from one phase to another? A. The substance loses or gains heat. B. The average kinet
lutik1710 [3]
I think the correct answer from the choices listed above is option B. When a substance changes from one phase to another, the average kinetic energy of the substance <span>changes since the molecules movements are changed as well. Hope this answers the question. Have a nice day.</span>
3 0
3 years ago
For each of the reactions, calculate the mass (in grams) of the product formed when 15.12g of the underlined reactant completely
Ludmilka [50]

Answer:

Part A : amount of product (KCl) =  28.88 g

Part B :  amount of product (KBr) =  46.13 g

Part C : amount of product (Cr₂O₃) =  17.3 g

Part D: amount of product (SrO) =  35.76 g

Explanation:

Part A:

Data Given:

Reaction :

                      2K(s) + Cl₂(g) --------> 2KCl

Amount of underline Reactant  (K) = 15. 12g

amount of other reactant = more than enough

Explanation:

As the Potassium (K) is 15.12g and other reactant that is chlorine is more than enough so the K is limiting reagent.

So, amount of product depend on the amount of Potassium (K)

Now Look at Given Reaction:

                                2K(s) + Cl₂(g) --------> 2KCl

                                2mol    1mol                 2mol

it shows that

2 mole of K give 2 mole of  KCl

if we represent mole in grams

Then

Molar mass of K = 39 g/mol

Molar mass of KCl = (39 + 35.5)

Molar mass of KCl = 74.5 g/mol

So the look again to reaction in terms of grams

                                      2K(s)     +    Cl₂(g) --------> 2KCl

                            2mole (39 g/mol)                      2mole (74.5 g/mol)

                                      78 g                                  149 g

Apply the Unity formula

                          78 g of Potassium ≅ 149 g of KCl

Then

                        15.12 g of Potassium ≅ how many g of Product (KCl)

By doing cross multiplication

               X g of Product (KCl) = 149 g of KCl  x 15.12 g of K /  78 g of K

              X g of Product (KCl) = 149 g of KCl  x 15.12 g of K /  78 g of K

              X g of Product (KCl) = 28.88 g

So the amount of product (KCl) =  28.88 g

_________________________________________

Part B:

Data Given:

Reaction :

                      2K(s) + Br₂(g) --------> 2KBr

Amount of underline Reactant  (K) = 15. 12g

amount of other reactant = more than enough

Explanation:

As the Potassium (K) is 15.12g and other reactant that is Bromine is more than enough so the K is limiting reagent.

So, amount of product depend on the amount of Potassium (K)

Now Look at Given Reaction:

                                2K(s) + Br₂(g) --------> 2KBr

                                2mol    1mol                 2mol

it shows that

2 mole of K give 2 mole of  KBr

if we represent mole in grams

Then

Molar mass of K = 39 g/mol

Molar mass of KBr = (39 + 80)

Molar mass of KBr =  119 g/mol

So, look again to reaction in terms of grams

                                      2K(s)     +    Br₂(g) --------> 2KBr

                            2mole (39 g/mol)                      2mole (119 g/mol)

                                      78 g                                  238 g

Apply the Unity formula

                          78 g of Potassium ≅  238 g of KBr

Then

                        15.12 g of Potassium ≅ how many g of Product (KBr)

By doing cross multiplication

               X g of Product (KBr) = 238 g of KBr  x 15.12 g of K /  78 g of K

              X g of Product (KBr) = 238 g of KBr  x 15.12 g of K /  78 g of K

              X g of Product (KBr) = 46.13 g

So the amount of product (KBr) =  46.13 g

__________________________________________

Part C:

Data Given:

Reaction :

                      4Cr(s) + 3O₂(g) --------> 2Cr₂O₃

Amount of underline Reactant  (Cr) = 15. 12g

amount of other reactant = more than enough

Explanation:

As the Chromium (Cr) is 15.12g and other reactant that is Oxygen is more than enough so the Cr is limiting reagent.

So, amount of product depend on the amount of Chromium (Cr)

Now Look at Given Reaction:

                                  4Cr(s) + 3O₂(g) --------> 2Cr₂O₃

                                  4mol      3mol                 2mol

it shows that

4 mole of Cr give 2 mole of  Cr₂O₃

if we represent mole in grams

Then

Molar mass of Cr = 52 g/mol

Molar mass of 2Cr₂O₃ = 2 [2 (52) + 3(16) ] = 2 (104+ 48)

Molar mass of  2Cr₂O₃ =  304 g/mol

So, look again to reaction in terms of grams

                                     4Cr(s) + 3O₂(g) --------> 2Cr₂O₃

                                 4 mol (52 g/mol)              2 mole (304 g/mol)

                                      208 g                                  608 g

Apply the Unity formula

                          208 g of Chromium ≅  608 g of Cr₂O₃

Then

                        15.12 g of Chromium ≅ how many g of Product (Cr₂O₃)

By doing cross multiplication

        X g of Product (Cr₂O₃) = 238 g of Cr₂O₃  x 15.12 g of Cr /  208 g of Cr

        X g of Product (Cr₂O₃) = 238 g of Cr₂O₃  x 15.12 g of Cr /  208 g of Cr

        X g of Product (Cr₂O₃) = 17.3 g

So the amount of product (Cr₂O₃) =  17.3 g

________________________________________

Part D:

Data Given:

Reaction :

                      2Sr(s) + O₂(g) --------> 2SrO(s)

Amount of underline Reactant  (Sr) = 15. 12g

amount of other reactant = more than enough

Explanation:

As the Strontium (Sr) is 15.12g and other reactant that is Oxygen is more than enough so the Sr is limiting reagent.

So, amount of product depend on the amount of Strontium (Sr)

Now Look at Given Reaction:

                                    2Sr(s) + O₂(g) --------> 2SrO(s)

                                    2mol      1mol              2mol

it shows that

2 mole of Sr give 2 mole of SrO

if we represent mole in grams

Then

Molar mass of Sr = 87.6 g/mol

Molar mass of 2SrO = 2 [87.6 + 16] = 2 (103.6)

Molar mass of 2SrO =  207.2 g/mol

So, look again to reaction in terms of grams

                                      2Sr(s) + O₂(g) --------> 2SrO(s)

                                 2 mol ( 87.6 g/mol)         2 mole (207.2 g/mol)

                                      175.2 g                                  414.4 g

Apply the Unity formula

                          175.2 g of Strontium ≅  414.4 g of SrO

Then

                        15.12 g of Strontium ≅ how many g of Product (SrO)

By doing cross multiplication

       X g of Product (SrO) = 414.4 g of SrO  x 15.12 g of Sr /  175.2 g of Sr

        X g of Product (SrO) = 414.4 g of SrO  x 15.12 g of Sr /  175.2 g of Sr

        X g of Product (SrO) = 35.76 g

So the amount of product (SrO) =  35.76 g

8 0
3 years ago
A three-carbon alkene contains two double bonds. Predict its molecular formula? A. C3H4 B. C3H5 C. C3H6
mestny [16]
The correct answer is A. C3H4 is the three-carbon alkene contains two double bonds. Alkenes are a class of organic compounds with carbon-carbon double bond. The structure for C3H4 is:
<span>
H2C=C=CH2</span>
7 0
4 years ago
"Thermite" reactions have been used for welding metal parts such as railway rails and in metal refining. One such thermite react
frosja888 [35]

<u>Answer:</u> The given reaction is non-spontaneous in nature.

<u>Explanation:</u>

Entropy change is defined as the difference in entropy of all the product and the reactants each multiplied with their respective number of moles.

The equation used to calculate entropy change is of a reaction is:

\Delta S^o_{rxn}=\sum [n\times \Delta S^o_{(product)}]-\sum [n\times \Delta S^o_{(reactant)}]

For the given chemical reaction:

3Mg(s)+Cr_2O_3(s)\rightarrow 3MgO(s)+2Cr(s)

The equation for the entropy change of the above reaction is:

\Delta S^o_{rxn}=[(3\times \Delta S^o_{(MgO(s))})+(2\times \Delta S^o_{(Cr(s))})]-[(3\times \Delta S^o_{(Mg(s))})+(1\times \Delta S^o_{(Cr_2O_3(s))})]

We are given:

\Delta S^o_{(Mg(s))}=32.68J/K.mol\\\Delta S^o_{(Cr_2O_3(s))}=81.2J/K.mol\\\Delta S^o_{(MgO(s))}=26.94J/K.mol\\\Delta S^o_{(Cr(s))}=23.77J/K.mol

Putting values in above equation, we get:

\Delta S^o_{rxn}=[(3\times (26.94))+(2\times (23.77))]-[(3\times (32.68))+(1\times (81.2))]\\\\\Delta S^o_{rxn}=-50.88J/K=-0.0509kJ/K.mol

For the reaction to be spontaneous, the Gibbs free energy of the reaction must come out to be negative.

To calculate the standard Gibbs free energy of the reaction, we use the equation:

\Delta G^o=\Delta H^o-T\Delta S^o

where,

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

\Delta H^o = standard enthalpy change of the reaction = 665.1 kJ/mol

T = Temperature = 298.15 K

\Delta S^o = standard entropy change of the reaction = -0.0509 kJ/K.mol

Putting values in above equation, we get:

\Delta G^o=(665.1kJ/mol)-(298.15K\times (-0.0509kJ/K.mol))=680.27kJ/mol

As, the Gibbs free energy of the reaction is coming out to be positive, the reaction is non-spontaneous in nature.

Hence, the given reaction is non-spontaneous in nature.

4 0
4 years ago
What factors does the kinetic energy of an object depend on
kogti [31]
The height it's falling, wind pressure, force, the weight of the object etc
8 0
3 years ago
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