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3 years ago

For #11 how to determine the signs?

Chemistry

2 answers:

vladimir1956 [14]3 years ago

6 0

They a all positive bro

Viefleur [7K]3 years ago

3 0

The first reaction is exothermic as it releases heat as shown by the '+ 48 kJ'. When a reaction is exothermic the enthalpy change (ΔH) is negative as the system is losing heat. The entropy change (ΔS) is also negative as 4 moles of gas are reacting to form 2 moles of gas, reducing the disorder in the system. Since the spontaneity of a reaction is governed by ΔG = ΔH - TΔS, where ΔG must be negative for a spontaneous reaction, the reaction is only spontaneous at low temperatures as both ΔH and ΔS are negative, so as temperature increases, so does ΔG, toward 0.
The second reaction is endothermic as it absorbs heat therefore having a positive ΔH, and a positive ΔS as one mole of liquid is converted to one mole of more disordered gas. Using the same equation as before it can be shown that the reaction is only spontaneous at higher temperatures. These answers all hold true for the 3rd reaction as well (i.e. positive ΔH, positive ΔS and spontaneous at high temperatures).
Finally, reaction 4 is exothermic, therefore negative ΔH, and has a positive ΔS as 2 moles in solution are produced from one mole of solid. Therefore using the equation shown before, ΔG will always be negative regardless of temperature, and therefore the reaction is always spontaneous.
Hope this helps! If you could I would greatly appreciate you making this the brainliest answer :) If you have any questions feel free to ask.

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Which of the following describes a property of water that helps sustain marine life forms?

Mariana [72]

Answer:

Open spaces in water's solid structure makes its solid state less dense than its liquid state.

Explanation:

Water unlike other liquids is special. It contracts when cooled, down to a temperature of 4°C but thereafter begins to expand as it reaches 0°C and turns into ice.
This property is useful for the preservation of marine life in very cold temperatures. During winter, the surface water in water lakes and rivers starts cooling. Upon reaching the temperature of 4°C, the surface water descends to the bottom as it denser.
This help in the maintenance of temperature of the water at the bottom at 4°C. It is in this layer that marine life is sustained.

4 0

3 years ago

Tin was among the first metals used by humans. Elemental tin is produced by heating tin(IV) oxide, the principal ore of tin, wit

insens350 [35]

<u>Answer:</u> The coefficient of carbon in the chemical reaction is 1.

<u>Explanation:</u>

A balanced chemical equation is defined as the equation in which total number of individual atoms on the reactant side is equal to the total number of individual atoms on product side.

Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.

The chemical equation for the reaction of tin (IV) oxide and carbon follows:

$SnO_2+C\rightarrow Sn+CO_2$

By Stoichiometry of the reaction:

1 mole of tin (IV) oxide reacts with carbon to produce 1 mole of elemental tin and carbon dioxide.

Hence, the coefficient of carbon in the chemical reaction is 1.

4 0

3 years ago

Bromo-4-fluorohexane has two chiral carbon atoms; therefore, the maximum number of possible stereoisomers that can be formed is

Zepler [3.9K]

Here we have to draw the four isomers of the compound 3-bromo-4-fluorohexane.

The four isomers of the compound is shown in the figure.

In an organic molecule the chiral -C center is that where four (4) different groups are present. In 3-bromo-4-fluorohexane the 3 and 4 positions are chiral centers. The possible isomers of a molecule can be obtained from the formula 2n. As here 2 chiral centers are present thus number of stereoisomers will be 2×2 = 4.

The four different isomers as shown in the figure are 3R-, 4R-; 3S-, 4S; 3R, 4S and 3S-, 4R- 3-bromo-4-fluorohexane.

In the 3-bromo-4-fluorohexane the functional groups are -Br, C₂H₅, -C₃H₆F and -H for 3-position and -F, -C₂H₅, -C₃H₆ and -H for 4-position respectively.

The priority of the -3 position will be Br > C₃H₆F > C₂H₅ > H and for -4 position F > C₃H₆Br > C₂H₅ > H. If the rotation from the higher priority group to lower is clockwise and anticlockwise then the S- and R- notation are used respectively. However if the -H atom is present at the horizontal position then the notation will be reverse.

Thus the four isomers of the compound is shown.

4 0

3 years ago

BRAINLIESTTT ASAP! PLEASE ANSWER IN YOUR OWN WORDS. :)

const2013 [10]

Answer:

The atomic structure of an atom involves 3 subatomic particles: the proton, neutron, and electron. The proton has a positive charge and is found in the core of the atom, with the neutral neutrons that also have a mass of 1 amu (atomic mass unit) just like the proton. The nucleus is the core of the atom and contains protons and neutrons and is practically the only area with mass. The electron cloud is basically an area surrounding the nucleus and it contains negative charged electrons. Electrons have no mass but are charged with a negative charge that keeps them. I really hope this helps :)

Explanation:

There is a helpful video that actually explains the structure of an atom in a rather fun way in just 2 minutes. It really does help big time and it's kinda funny if you look it up on YT and watch:

WKRP: Venus Explains the Atom

Have a wonderful great day :)

8 0

3 years ago

Help me for brainlest pleaes

Tresset [83]

First option.

The male tails are more attractive because of their long feathers , meanwhile the female tails are shorter than expected!

6 0

3 years ago