Which of the following items is NOT a compound?

How many atoms are in 1.4 mol of phosphorus trifluoride (PF3)?

Trava [24]

One mol is equal to the Avogadro's Number. Using this equivalence, we can obtain the number of molecules contained in 1.4 mol:

$1.4\ mol\ PF_3\cdot \frac{6.022\cdot 10^{23}\ molec}{1\ mol} = 8.43\cdot 10^{23}\ molec\ PF_3$

Each molecule contains 4 atoms: three atoms of fluorine and one atom of phosphorus:

$8.43\cdot 10^{23}\ molec\ PF_3\cdot \frac{4\ atoms}{1\ molec\ PF_3} = \bf 3.37\cdot 10^{23}\ atoms$

Is there any mistake in my English? Please let me know!

6 0

4 years ago

Calculate the boiling point (in degrees C) of a solution made by dissolving 7 g of naphthalene {C10H8} in 14.4 g of benzene. The

never [62]

Answer:

The boiling point = 89.69 °C

Explanation:

Step 1: Data given

Mass of naphthalane = 7.0 grams

Mass of benzene = 14.4 grams

The Kbp of the solvent = 2.53 K/m

The normal boiling point is 80.1°C

Naphthalene, C10H8 , is a non-electrolyte, which means that the van't Hoff factor for this solution will be 1

Step 2: Calculate moles naphthalene

Moles naphthalene = mass / molar mass

Moles naphthalene = 7.0 grams / 128.17 g/mol

Moles naphthalene = 0.0546 moles

Step 3: Calculate molality

Molality = moles naphthalene / mass water

Molality = 0.0546 moles / 0.0144 kg

Molality = 3.79 molal

Step 4:

ΔT = i*Kb*m

ΔT = 1*2.53 K/m * 3.79 molal

ΔT = 9.59 °C

The boiling point = 80.1 °C + 9.59 °C = 89.69 °C

3 0

3 years ago

1. What is the state of matter of each of these materials at room temperature? a) gold b) gasoline c) oxygen d) olive oil e) mer

ehidna [41]

Answer:

a) gold - Solid

b) gasoline - liquid

c) oxygen - gaseous

d) olive oil - liquid

e) mercury (found in thermometers) - liquid

f) aluminum - solid

Explanation:

Matter exists in three states viz: solid, gas and liquid. Note that, room temperature is a neither hot or cold temperature, which is about 20-23°C.

A) Gold is a transition metal with the symbol Au. At a room temperature, Gold, like most metals are found as SOLIDS.

B) Gasoline is a liquid mixture of refined hydrocarbons majorly used as fuels.

C) Oxygen is a chemical element with symbol O. It is a constituent of natural air, which is a mixture of different gases including oxygen. Hence, at room temperature, Oxygen is a gas.

D) Olive oil is a vegetable oil got from olives. It is composed of fats and it's a liquid at room temperature.

E) Mercury is an element with symbol Hg. It is the only metallic element found naturally (at room temperature) as a liquid. It is used in thermometers.

F) Aluminum is another chemical element with symbol Al. It is a lustrous metal that occurs as a Solid in room temperature.

8 0

3 years ago

Consider this reaction:

nadya68 [22]

11.7 g hope this helps and have a great day

4 0

2 years ago

The stock concentration of NaOH is 0.5M. 0.5M = 0.500mol/1.0L.

valentinak56 [21]

Answer:a) 0.1 mole. b) 4g. c) 2% d) 196 mL

Explanation: in 200mL , 0.1mole

mw NaOH = 40g/mol —> 4g in 0.1 mole

4g in 200mL so 2g in 100mL

density NaOH = 1g/mL so if 4g in 200 mL, 4mL , 196 mL water

5 0

3 years ago