37. How many grams does 4.00 moles of H20 weigh?

A chemist prepares a solution by adding 258 mg of K2Cr2O7 (MW = 294.19 g/mol ) to a volumetric flask, and then adding water unti

Maksim231197 [3]

Answer: Molarity of the prepared solution is $1.75\times 10^{-3}mole/L$

Explanation:

Molarity is defined as the number of moles of solute dissolved per liter of the solution.

$Molarity=\frac{n\times 1000}{V_s}$

where,

n= moles of solute

$V_s$ = volume of solution in ml = 500 ml

moles of solute = $\frac{\text {given mass}}{\text {molar mass}}=\frac{0.258g}{294.19g/mol}=8.77\times 10^{-4}mol$

Now put all the given values in the formula of molarity, we get

$Molarity=\frac{8.77\times 10^{-4}moles\times 1000}{500ml}=1.75\times 10^{-3}mole/L$

Thus molarity of the prepared solution is $1.75\times 10^{-3}mole/L$

3 0

3 years ago

Suppose the half-life is 9.0 s for a first order reaction and the reactant concentration is 0.0741 M 50.7 s after the reaction s

bazaltina [42]

<u>Answer:</u> The time taken by the reaction is 84.5 seconds

<u>Explanation:</u>

The equation used to calculate half life for first order kinetics:

$k=\frac{0.693}{t_{1/2}}$

where,

$t_{1/2}$ = half-life of the reaction = 9.0 s

k = rate constant = ?

Putting values in above equation, we get:

$k=\frac{0.693}{9}=0.077s^{-1}$

Rate law expression for first order kinetics is given by the equation:

$k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}$ ......(1)

where,

k = rate constant = $0.077s^{-1}$

t = time taken for decay process = 50.7 sec

$[A_o]$ = initial amount of the reactant = ?

[A] = amount left after decay process = 0.0741 M

Putting values in equation 1, we get:

$0.077=\frac{2.303}{50.7}\log\frac{[A_o]}{0.0741}$

$[A_o]=3.67M$

Now, calculating the time taken by using equation 1:

$[A]=0.0055M$

$k=0.077s^{-1}$

$[A_o]=3.67M$

Putting values in equation 1, we get:

$0.077=\frac{2.303}{t}\log\frac{3.67}{0.0055}\\\\t=84.5s$

Hence, the time taken by the reaction is 84.5 seconds

6 0

4 years ago

List three forms of potential energy

kolezko [41]

Answer:

elastic potential gravitational potential chemical potential

Explanation:

i really hoped this helped

7 0

3 years ago

Read 2 more answers

"0.35 g of hydrogen chloride (hcl is dissolved in water to make 3.0 l of solution. what is the ph of the resulting hydrochloric

Nastasia [14]

Firstly calculating number of moles of hcl disssolved. The answer would be in the pic above. Concentration of hydrogen ions can be calculated by using that mole amount dividing by 3litres of solution to get 0.003196. Hence the ph of solution will be -log10(h+ concentration) which is equal to 2.495

8 0

3 years ago

In a certain organic compound, one of the carbon atoms is bonded to three atoms. One of these is a carbon atom and the other two

Arisa [49]

A double covalent bond.

<h3>Explanation</h3>

As their name suggest, ionic bonds are forces between ions of opposite charges. Ionic bonds involve the transfer of electrons from one atom to another. Such transfer can't occur between two carbon atoms. They belong to the same element and have the same tendency to gain or lose electrons. As a result, the bond between them cannot be ionic.

Ion dipole is a force <em>between</em> an ion and a molecule. The bond between the two carbon atoms is located <em>within</em> an organic molecule. The force between the two carbon atoms can't be ion dipole, either.

There are four valence electrons in each carbon atom. Each of them needs four more electrons to achieve an octet. They would achieve that octet by sharing four electrons with other atoms. Each shared electron pair acts as a covalent bond. Each hydrogen atom demands one more electron and would share only one electron with the carbon atom. The first carbon atom in this question shared two electrons with two hydrogen atoms. It needs to share two more with the other carbon atom so that it could achieve an octet. As a result, it would share two pairs of electrons, which will make a double covalent bond between the two carbon atoms.

6 0

3 years ago