Identify the total number of molecules in the chemical formula: 6CH4 a 6 b 10 c 24 d 30

(b) The mass of a single molybdenum atom is 1.59×10-22 g. Suppose enough Mo atoms were lined up like beads on a string to span a

serious [3.7K]

Answer:N=1151724138 atoms

Explanation:The atomic radius of molybdenum atom is 145 picometers so lining up molybdenum atoms is like lining up the beads of radius 145 picometers

so one bead would cover the length of 145*2=290 picometers

hence the atom's diameter =D=290 picometers

D=290 *10^(-12)

$D=290/1000000000000$

also

Distance span= 33.4 cm

Distance span= 0.334m

As the Distance span adds up with no of atoms the resulting formula is

Distance span by atoms= No of atoms * atom's diameter

so

$N=\frac{Distance Spaned}{Atom's Diameter } \\N=0.334/(0.000000000290)\\N=1151724138 atoms$

4 0

2 years ago

What is Kb for N2H4 if the pH of a 0.158M solution of N2H5Cl is 4.5?

olasank [31]

Answer:

Kb $= 1.58 * 10^{-6}$

Explanation:

The correct question is

What is Kb for N2H4 if the pH of a 0.158M solution of N2H5Cl is 4.5?

Solution-

N2H4Cl hydrolyses on addition of water

The reaction equation is as follows -

N2H4+ + H2O ----> N2H4 + H3O+

$Ka = \frac{K_w}{K_b} = \frac{10^{-14}}{K_b}$

pH $= 4.5$

$[H+] = 10^{-pH} = 10^{-4.5}$

$K_b= \frac{10^{-14} }{K_b} = \frac{Y_2}{0.158} \\K_b= \frac{(10^{-4.5})^2}{0.158}\\=> Kb = 0.158 * 10-14 /(10-4.5)2$

Kb $= 1.58 * 10^{-6}$

3 0

2 years ago

What are elements in the tall columns of the periodic table called?

mihalych1998 [28]

They are called representative elements.

6 0

2 years ago

Read 2 more answers

What is true of a compound?

zalisa [80]

Answer:

It does not always retain the properties of the substances that make it up

Explanation:

7 0

3 years ago

Read 2 more answers

A 10.0 g ice cube is placed into 250 g of water with an initial temperature of 20.0 C. If the water drops to a temperature of 16

Radda [10]

the mass of ice taken = 10 g

the mass of water = 250 g

initial temperature of water = 20 C

the final temperature of water = 16. 8 C

specific heat of water = 4.18 J/g*K

the heat absorbed by ice to melt = heat loss by water

heat loss by water = mass X specific heat of water X change in temperature

heat loss by water = 250 X 4.18 X (20-16.8) = 3344 Joules

heat gained by ice = 3344 J

heat gained by ice = enthalpy of fusion X moles of ice

moles of ice = mass / molar mass = 10 / 18 = 0.56 moles

enthalpy of fusion = 3344 / 0.56 = 5971.43 J / mole

3 0

2 years ago