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quester [9]
3 years ago
11

Which statement is FALSE? a. ΔHrxn is the heat of reaction. b. ΔErxn is a measure of heat. c. An exothermic reaction gives heat

off heat to the surroundings. d. Endothermic has a positive ΔH. e. Enthalpy is the sum of a system's internal energy and the product of pressure and volume.
Chemistry
1 answer:
Pavlova-9 [17]3 years ago
3 0

Answer:

b. ΔE rxn is a measure of heat

Explanation:

a. ΔHrxn is the heat of reaction. <em>TRUE. </em>ΔHrxn or change in enthalpy of reaction is per definition the change in heat that is involved in a chemical reaction.

b. ΔErxn is a measure of heat. <em>FALSE. </em>Is the change in internal energy of a reaction

c. An exothermic reaction gives heat off heat to the surroundings. <em>TRUE</em>. An exothermic reaction is a chemical reaction that releases heat.

d. Endothermic has a positive ΔH. <em>TRUE. </em>When a process is exothermic ΔH<0 and when the process is endothermic ΔH>0

e. Enthalpy is the sum of a system's internal energy and the product of pressure and volume. <em>TRUE. </em>Under constant pressure and volume the formula is ΔH = ΔE + PV

I hope it helps!

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In each case, decide if the change is a "chemical change" or a "physical change". a) A cup of household bleach changes the color
Crazy boy [7]

Answer:A cup of household bleach changes the color of your favorite T-shirt from purple to pink. - chemical change

Water vapor in your exhaled breath condenses in the air on a cold day.- physical change

Plants use carbon dioxide from the air to make sugar.- chemical change

Butter melts when placed in the Sun- physical change

Explanation:

A chemical change leads to the formation of a new substance and is not easily reversible. A physical change does not lead to the formation of a new substance and is easily reversible. Physical changes include condensation, melting,etc while a chemical change is a chemical reaction.

8 0
3 years ago
Based on the current atomic theory most chemical reaction take place as a result of the interactions of which sub- atomic partic
icang [17]
Electrons, everything is pretty much based around the likeliness of electrons to be swapped or shared between atoms
6 0
2 years ago
Calculate the electric double layer thickness of a alumina colloid in a dilute (0.1 mol/dm3) CsCI electrolyte solution at 30 °C.
Ad libitum [116K]

Explanation:

The given data is as follows.

    Concentration = 0.1 mol/dm^{3}

                             = 0.1 \frac{mol dm^{3}}{dm^{3}} \frac{10^{3}}{dm^{3}} \times \frac{6.022 \times 10^{23}}{1 mol} ions

                             = 6.022 \times 10^{25} ions/m^{3}

               T = 30^{o}C = (30 + 273) K = 303 K

Formula for electric double layer thickness (\lambda_{D}) is as follows.

            \lambda_{D} = \frac{1}{k} = \sqrt \frac{\varepsilon \varepsilon_{o} K_{g}T}{2 n^{o} z^{2} \varepsilon^{2}}

where, n^{o} = concentration = 6.022 \times 10^{25} ions/m^{3}

Hence, putting the given values into the above equation as follows.

                 \lambda_{D} = \sqrt \frac{\varepsilon \varepsilon_{o} K_{g}T}{2 n^{o} z^{2} \varepsilon^{2}}                    

                          = \sqrt \frac{78 \times 8.854 \times 10^{-12} c^{2}/Jm \times 1.38 \times 10^{-23}J/K \times 303 K}{2 \times 6.022 \times 10^{25} ions/m^{3} \times (1)^{2} \times (1.6 \times 10^{-19}C)^{2}}  

                         = 9.669 \times 10^{-10} m

or,                     = 9.7 A^{o}

                          = 1 nm (approx)

Also, it is known that \lambda_{D} = \sqrt \frac{1}{n^{o}}

Hence, we can conclude that addition of 0.1 mol/dm^{3} of KCl in 0.1 mol/dm^{3} of NaBr "\lambda_{D}" will decrease but not significantly.

7 0
3 years ago
How molecular structure affects solubility?
spayn [35]

Answer:

The molecular structure affects solubility mainly biased on its polarity or bonded ions.

Explanation:

Polar molecules will better interact with the water molecules and will dissolve easier. Nonpolar molecules can dissolve if they are small enough, however they don't interact well with the polar molecules. Bonded ions, such as NaCl split into a cation Na and an anion Cl which the positive charge on the Na will be attracted to the oxygen, and the negatively charged Cl will be attracted to the positive Hydrogen.

**Remember this rule, like dissolves like, meaning nonpolar dissolves nonpolar and polar dissolves polar.

I hope this helps!

7 0
2 years ago
g Which ONE of the following pure substances will exhibit hydrogen bonding? A) methyl fluoride, FCH3 B) dimethyl ether, CH3C–O–C
luda_lava [24]

Answer:

C) formaldehyde, H2C=O.

Explanation:

Hello,

In this case, given that the hydrogen bondings are known as partial intermolecular interactions between a lone pair on an electron rich donor atom, particularly oxygen, and the antibonding molecular orbital of a bond between hydrogen and a more electronegative atom or group. Thus, among the options, C) formaldehyde, H2C=O, will exhibit hydrogen bonding since the lone pair of electrons of the oxygen at the carbonyl group, are able to interact with hydrogen (in the form of water).

Best regards.

8 0
3 years ago
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