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3 years ago

Which statement is true if the Hrxn of a reaction is positive?

Chemistry

2 answers:

erma4kov [3.2K]3 years ago

7 0

I think it is b..................................................

iren2701 [21]3 years ago

3 0

Answer: The correct answer is Option A.

Explanation:

Endothermic reactions are defined as the reactions in which potential energy of the reactants is less than the potential energy of the products. The total enthalpy change of the reaction $(\Delta H_{rxn})$ comes out to be positive. Energy is absorbed during this reaction.

$\Delta H_{rxn}=\Delta H_{products}-\Delta H_{reactants}=+ve$

Exothermic reactions are defined as the reactions in which potential energy of the products is less than the potential energy of the reactants. The total enthalpy change of the reaction $(\Delta H_{rxn})$ comes out to be negative. Energy is released during this reaction.

$\Delta H_{rxn}=\Delta H_{products}-\Delta H_{reactants}=-ve$

From the above information, the correct answer is Option A.

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Which pair of elements will form a covalent bond?

Dominik [7]

Answer: Option (A) is the correct answer.

Explanation:

A covalent bond is formed when there occurs sharing of electrons between atoms.

For example, in hydrogen atom there is one electron in its orbit and in a chlorine atom there is 7 valence electron. So, in order to attain stability both hydrogen and chlorine share electrons when they come close to each other.

Whereas except hydrogen and chlorine rest of the given atoms will form ionic bond, that is, bond formed by transfer of electrons.

Thus, we can conclude that a pair of hydrogen and chlorine will form a covalent bond.

7 0

3 years ago

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Explain the law of conservation of energy. Give a specific example using kinetic and potential energy that shows how energy is c

stira [4]

Answer:

Law of conservation of energy states that energy can neither be created nor can be destroyed but can be changed from one form to another

example:I am quite confused Sorry....❤plz follow me

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3 years ago

If a 95.27 mL sample of acetic acid (HC2H3O2) is titrated to the equivalence point with 79.06 mL of 0.113 M KOH, what is the pH

KATRIN_1 [288]

Answer:

8.73

Explanation:

The concentration of acetic acid can be determined as follows:

$M_1V_1 = M_2V_2\\(KOH) = (CH_3COOH)$

$M_{KOH}=0.113 M\\V_{KOH}=79.06 mL$

$V_{CH_3COOH}=95.27 \\\\M_{CH_3COOH)=?????$

$M_{CH3COOH} = \frac{M_{KOH}*V_{KOH}}{V_{CH_3COOH}}$

$M_{CH3COOH} = \frac{0.113*79.06}{95.27}$

$M_{CH3COOH} = 0.094 M$

Moles of $CH_3COOH$ = $95.27* 10^{-3}* 0.094$

=0.0090 moles

Moles of $KOH = 79.06*10^{-3}*0.113$

= 0.0090 moles

The equation for the reaction can be expressed as :

$CH_3COOH$ $+$ $KOH$ -----> $CH_3COO^{-}K^+$ $+$ $H_2O$

Concentration of $CH_3COO^{-$ ion = $\frac{0.0090}{Total volume (L)}$

= $\frac{0.0090}{(95.27+79.06)} *1000$

= 0.052 M

Hydrolysis of $CH_3COO^{-$ ion:

$CH_3COO^{-$ $+$ $H_2O$ -----> $CH_3COOH$ $+$ $OH^-$

$K = \frac{K_w}{K_a} = \frac{x*x}{0.052-x}$

⇒ $\frac{10^{-14}}{1.82*10^{-5}}= \frac{x*x}{0.052-x}$

= $0.5494*10^{-9}= \frac{x*x}{0.052-x}$

As K is so less, then x appears to be a very infinitesimal small number

0.052-x ≅ x

$0.5494*10^{-9}= \frac{x^2}{0.052}$

$x^2 = 0.5494*10^{-9}*0.052$

$x^2 = 0.286*10^{-10$

$x = \sqrt{0.286*10^{-10$

$x =0.535*10^{-5}M$

$[OH] = x =0.535*10^{-5}$

$pOH = -log[OH^-]$

$pOH = -log[0.535*10^{-5}]$

$pOH = 5.27$

pH = 14 - pOH

pH = 14 - 5.27

pH = 8.73

Hence, the pH of the titration mixture = 8.73

8 0

3 years ago

What is the mass of 3.25 mol of h2so4

Setler [38]

Answer/ explanation :

The find the mass,

We use this formula

Number of mole = mass/ molar mass

Since number of mole = 3.25mol

Number of mass be x

Molar mass of H2SO4

H - 1.00784 * 2= 2.01568

S - 32.065

O - 15.999 * 4 = 63.996

Note there are 2 moles of H and 4 moles of O and 1 mole of S

Molar mass of H2SO4 = 2.01568 + 32.065 + 63.996

= 98.07668g/mol

Number of mole= 3.25mol

3.25 = x / 98.07668

x = 3.25 * 98.07668

= 318.749g

Therefore, the number of mass is 318.749g

7 0

3 years ago

You have a board, wood blocks, and a toy car. Your goal is to build a ramp that sends the car as far across the floor as possibl

lakkis [162]

Answer:

<h3>The board should be placed at about an 80-88 degrees angle. </h3>

Explanation:

This will speed the car up and increase its speed as going down the ramp.

5 0

3 years ago

Read 2 more answers