How many meters in 1000 mm

24 how many moles are in 2.04 × 1024 molecules of h2o?

Sergeeva-Olga [200]

The answer is 3.39 mol.

Avogadro's number is the number of molecules in 1 mol of substance.
6.02 × 10²³ molecules per 1 mol.
2.04 × 10²⁴ molecules per x.

6.02 × 10²³ molecules : 1 mol = 2.04 × 10²⁴ molecules : x
x = 2.04 × 10²⁴ molecules * 1 mol : 6.02 × 10²³ molecules
x = 2.04/ 6.02 × 10²⁴⁻²³ mol
x = 0.339 × 10 mol
x = 3.39 mol

8 0

3 years ago

The work function for metallic potassium is 2.3 eV. Calculate the velocity in km/s for electrons ejected from a metallic potassi

mote1985 [20]

Answer:

932.44 km/s

Explanation:

Given that:

The work function of the magnesium = 2.3 eV

Energy in eV can be converted to energy in J as:

1 eV = 1.6022 × 10⁻¹⁹ J

So, work function = $2.3\times 1.6022\times 10^{-19}\ J=3.68506\times 10^{-19}\ J$

Using the equation for photoelectric effect as:

$E=\psi _0+\frac {1}{2}\times m\times v^2$

Also, $E=\frac {h\times c}{\lambda}$

Applying the equation as:

$\frac {h\times c}{\lambda}=\psi _0+\frac {1}{2}\times m\times v^2$

Where,

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

m is the mass of electron having value $9.11\times 10^{-31}\ kg$

$\lambda$ is the wavelength of the light being bombarded

$\psi _0=Work\ function$

v is the velocity of electron

Given, $\lambda=260\ nm=260\times 10^{-9}\ m$

Thus, applying values as:

$\frac{6.626\times 10^{-34}\times 3\times 10^8}{260\times 10^{-9}}=3.68506\times 10^{-19}+\frac{1}{2}\times 9.11\times 10^{-31}\times v^2$

$3.68506\times \:10^{-19}+\frac{1}{2}\times \:9.11\times \:10^{-31}v^2=\frac{6.626\times \:10^{-34}\times \:3\times \:10^8}{260\times \:10^{-9}}$

$\frac{1}{2}\times 9.11\times 10^{-31}\times v^2=7.64538\times 10^{-19}-3.68506\times 10^{-19}$

$\frac{1}{2}\times 9.11\times 10^{-31}\times v^2=3.96032462\times 10^{-19}$

$v^2=0.869446\times 10^{12}$

v = 9.3244 × 10⁵ m/s

Also, 1 m = 0.001 km

So, v = 932.44 km/s

5 0

3 years ago

A sample of gas initially occupies 4.25 L at a pressure of 0.850 atm at 23.0°C. What will the volume be if the temperature is ch

Akimi4 [234]

Answer:

$2.31\text{ L}$

Explanation:

Here, we want to calculate the final volume

We use the general gas equation here:

$\frac{P_1V_1}{T_1}\text{ = }\frac{P_2V_2}{T_2}$

P1 is the initial pressure which is 0.850 atm

V1 is the initial volume which is 4.25 L

T1 is the initial temperature which is (23 + 273.15 = 296.15 K)

P2 is the final pressure which is 1.50 atm

V2 is the final volume which is unknown

T2 is the final temperature (11.5 + 273.15 = 284.65 K)

Substituting the values, we have:

$\begin{gathered} \frac{0.850\text{ }\times4.25}{296.15}\text{ = }\frac{1.50\times V_2}{284.65} \\ \\ V_2\text{ = }\frac{284.65\text{ }\times0.850\times4.25}{1.5\times296.15} \\ \\ V_2\text{ = 2.31 L} \end{gathered}$

6 0

1 year ago

Gold has a density of about 20.0g/mL this means that each milliliter has a mass of about __ grams.

qwelly [4]

Answer:

20.0 grams

Explanation:

If the density of gold is 20.0 g/mL, then we can multiply it by 1 mLto find the weight of 1 mL of gold.

20.0 $\frac{grams}{mL}$ *1mL=20.0 grams