How many nucleons are there in an atom with a nuclear charge of +20 and 23 neutrons?

Codeine C18H21NO3 is a weak organic base. A 5.0 x 10^-3 M solution of codeine has a pH of 9.95. Calculate the value of Kb for th

arsen [322]

Answer:

Kb = $4.45\times10^{-7}\ mol/L$

$p^{Kb}=6.35$

Explanation:

For a weak organic base, the formula to find $p^{OH}$ is given by:

$p^{OH}=p^{K_b}+\log c$

where c is the concentration of base.

Here c= $5\times10^{-3}\ M$

$p^{H}=9.95\\p^{OH}=14-p^{H}=14-9.95=4.05$

Substituting the above values in the formula,we get:

$p^{k_b}=p^{OH}-\log c\\p^{k_b}=4.05-\log (5\times10^{-3})\\p^{K_b}=6.35\\K_b=$antilog 6.35=4.45\times10^{-7}\ mol/L$

Hence:

Kb = $4.45\times10^{-7}\ mol/L$

$p^{Kb}=6.35$

7 0

2 years ago

Water (10 kg/s) at 1 bar pressure and 50 C is pumped isothermally to 10 bar. What is the pump work? (Use the steam tables.) O -7

11Alexandr11 [23.1K]

Explanation:

For an isothermal process equation will be as follows.

W = nRT ln $\frac{P_{1}}{P_{2}}$

It is given that mass is 10 kg/s or 10,000 g/s (as 1 kg = 1000 g). So, calculate number of moles of water as follows.

No. of moles = $\frac{mass}{\text{molar mass}}$

= $\frac{10000 g/s}{18 g/mol}$

= 555.55 mol/s

= 556 mol/s (approx)

As T = $50^{o}C$ or (50 + 273.15) K = 323.15 K. Hence, putting the given values into the above formula as follows.

W = nRT ln[/tex]\frac{P_{1}}{P_{2}}[/tex]

= $556 mol/s \times 8.314 J/ K mol K \times 323.15 K \times ln\frac{1}{10}$

= $556 mol/s \times 8.314 J/ K mol K \times 323.15 K \times -2.303$

= -3440193.809 J/s

Negative sign shows work is done by the pump. Since, 1 J = 0.001 kJ. Therefore, converting the calculated value into kJ as follows.

$3440193.809 J/s \times \frac{0.001 kJ}{1 J}$

= 3440.193 kJ/s

= 3451 kJ/s (approx)

Thus, we can conclude that the pump work is 3451 kJ/s.

6 0

3 years ago

I have a mixture of sand salt and water from the sea. Describe in detail how I separate these three substances and explain why e

Ivanshal [37]

Answer:

You can separate a mixture of sand, salt and water by decantation and evaporation. Decantation will separate sand from salt and water. Sand remains in the original vessel, whereas salt and water is transfered to new vessel. Evaporation will separate salt from water.

3 0

1 year ago

Identify two physical properties and two chemical properties of a bag of microwave popcorn before popping and after

krek1111 [17]

Physical properties of a bag of microwaveable popcorn are the mass of it, the color of it, the size of it, and the weight of it. Two chemical properties of a bag of microwavable popcorn are it changed from seeds to popcorn and it popped.

4 0

3 years ago

Read 2 more answers

Which statement would be the most useful for deriving the ideal gas law

Anvisha [2.4K]

Volume is directly proportional to the number of moles

8 0

3 years ago

Read 2 more answers