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kupik [55]
3 years ago
15

Which statement about Delta.Hf is true?

Chemistry
2 answers:
Novay_Z [31]3 years ago
3 0

Answer:

  • <u><em>It is positive when the bonds of the product store more energy than those of the reactants.</em></u> (the second statement)

Explanation:

ΔHf is the change of enthalpy during the reaction, which is equal to the sum of enthaply  changes of the products less the sum of the enthalpy changes of the reactants.

  • ΔHf = ∑ (ΔH products)  - ∑ (ΔH reactants)

  • ΔHf = ΔH rxn

Also, ΔHrxn, per definition, is the potential chemical energy stored in the bonds of the products less the chemical potential energy stored in the bonds of the reactants.

Then, when the potential chemical energy stored in the bonds of the products is greater than the chemical potential energy stored in the bonds of the reactants ΔHrxn is positive.

Hence, you conclude that ΔHf is positive when the bonds of the product store more energy than those of the reactants (second statement from the choices).

Some brief comments about the other statements:

  • The standard enthalpy of formation, ΔHf, is zero for an element in its standard state, not for a compound.

  • For a compound the enthalpy of formation at 25ºC and 1 atm (the standard state) may be positive or negative.

  • Also, note that the standard state for any element is not liquid: some are solids, some are gases, and some are liquids at 25ºC and 1 atm.

mote1985 [20]3 years ago
3 0

Answer:

B

Explanation:

answer on edg :)

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If 16.0 mL of acetone is dissolved in water to make 155 mL of solution what is the concentration expressed in volume/volume % of
Lady_Fox [76]
Percentage by volume of solution is the percentage volume of solute in total volume of solution.
Volume percentage (v/v%) = volume of solute / total volume of solution x 100%
volume of solute - 16.0 mL
total volume of solution - 155 mL 
v/v% = 16.0 / 155 x 100% = 10.32%
this means that in a volume of 100 mL solution, 10.32 mL is acetone.
7 0
3 years ago
Draw an electrolytic cell in which Mn2+ is reduced to Mn and Sn is oxidized to Sn2+. (Assume standard conditions).
babunello [35]

Answer:

-1.05 V

Explanation:

A detailed diagram of the setup as required in the question is shown in the image attached to this answer. The electrolytes chosen are SnCl2 for the anode half cell and MnCl2 for the cathode half cell. Tin rod and manganese rod are used as the anode and cathode materials respectively. Electrons flow from anode to cathode as indicated. The battery connected to the set up drives this non spontaneous electrolytic process.

Oxidation half equation;

Sn(s) ------> Sn^2+(aq) + 2e

Reduction half equation:

Mn^2+(aq) + 2e ----> Mn(s)

Cell voltage= E°cathode - E°anode

E°cathode= -1.19V

E°anode= -0.14 V

Cell voltage= -1.19 V - (-0.14V)

Cell voltage= -1.05 V

8 0
3 years ago
What is the maximum amount of CO2
Wittaler [7]

Answer:

10.6 g CO₂

Explanation:

You have not been given a limiting reagent. Therefore, to find the maximum amount of CO₂, you need to convert the masses of both reactants to CO₂. The smaller amount of CO₂ produced will be the accurate amount. This is because that amount is all the corresponding reactant can produce before it runs out.

To find the mass of CO₂, you need to (1) convert grams C₂H₂/O₂ to moles (via molar mass), then (2) convert moles C₂H₂/O₂ to moles CO₂ (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles CO₂ to grams (via molar mass). *I had to guess the chemical reaction because the reaction coefficients are necessary in calculating the mass of CO₂.*

C₂H₂ + O₂ ----> 2 CO₂ + H₂

9.31 g C₂H₂            1 mole               2 moles CO₂          44.0095 g
------------------  x  -------------------  x  ----------------------  x  -------------------  =
                            26.0373 g           1 mole C₂H₂              1 mole

=  31.5 g CO₂

3.8 g O₂             1 mole               2 moles CO₂          44.0095 g
-------------  x  --------------------  x  ----------------------  x  --------------------  =
                       31.9988 g              1 mole O₂                 1 mole

=  10.6 g CO₂

10.6 g CO₂ is the maximum amount of CO₂ that can be produced. In other words, the entire 3.8 g O₂ will be used up in the reaction before all of the 9.31 g C₂H₂ will be used.

8 0
2 years ago
Which of the following is a correct lewis structure for sulfur dioxide, so2?
pshichka [43]

The correct Lewis structure of SO2 is the Lewis structure that shows all the 12 valence electrons in the molecule.

A Lewis structure shows the number of valence electrons on the valence shell of all the atoms in a compound. The electrons are shown as dots around the symbol of each element or a dash to indicate shared electrons in a covalent bond.

Looking at the Lewis structure of SO2 attached to this answer, we can see the twelve valence electrons in the molecule and how they are distributed around each atom as shown.

Learn more: brainly.com/question/20514601

3 0
2 years ago
Maalox is the trade name for an antacid and antigas medication used for relief of heartburn, bloating, and acid indigestion. Eac
Sholpan [36]

Maalox is the trade name for an antacid and antigas medication used for relief of heartburn, bloating, and acid indigestion in which

4 ml contains

= 320mg of aluminum hydroxide

= 320mg of magnesium hydroxide

= 32mg of simethicone

recommended doses = 4 times * 2 tea spoon = 8 tea spoon/ day

given = 1 tea spoon = 5 ml

8 tea spoon = 40 ml

hence,

amount of aluminum hydroxide = 320/4 * 40 = 3200mg = 3.2 g

amount of magnesium hydroxide = 320/4 * 40 = 3.2 g

amount of  simethicone = 32/4 * 40 = 320 mg = 0.32g

To know more about antacid visit :

brainly.com/question/1328376

#SPJ9

8 0
1 year ago
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