All categories

3 years ago

Calculate the number of ammonia molecules in 3.9 g.

1 answer:

6 0

•3.9g of ammonia
•molar mass of ammonia = 17.03g/mol

1st you have to covert grams to moles by dividing the mass of ammonia with the molar mass:

(3.9 g)/ (17.03g/mol) = 0.22900763mols

Then convert the moles to molecules by multiplying it with Avogadro’s number:

Avogadro’s number: 6.022 x 10^23

0.22900763mols x (6.022 x 10^23 molecs/mol)
= 1.38 x 10^23 molecules

You might be interested in

Throughout the reflection, make sure you have a copy of the Student Guide and your data tables. Use the drop-

Inessa05 [86]

Answer:

1) mass and type of material

2) type of material

3) temperature

Explanation:

8 0

2 years ago

A 0.500-g sample of KCl is added to 50.0g of water in a calprimeter (Figure 5.12) If the temperature decreases by 1.05C. what is

Sauron [17]

Answer : The reaction is endothermic.

Explanation :

Formula used :

$Q=m\times c\times \Delta T$

where,

$\Delta T$ = change in temperature = $1.05^oC$

Q = heat involved in the dissolution of KCl = ?

m = mass = 0.500 + 50.0 = 50.5 g

c = specific heat of resulting solution = $4.18J/g^oC$

Now put all the given value in the above formula, we get:

$Q=50.5g\times 4.18J/g^oC\times 1.05^oC$

$Q=+221.64J$

The heat involved in the dissolution of KCl is positive that means as the change in temperature decreases then the reaction is endothermic and as the change in temperature increases then the reaction is exothermic.

Hence, the reaction is endothermic.

8 0

3 years ago

determine mass of water formed when 12.5 L NH3(at298K and 1.50atm) is reacted with 18.9L of O2 (at 323K and 1.1atm)

sasho [114]

The mass of water formed is

calculation

Use the ideal gas equation to calculate the moles of NH3 and O2

that is Pv= n RT

where; P= pressure,

V= volume,

n = number of moles,

R=gas constant = 0.0821 l .atm/ mol.K

make n the formula of the subject by diving both side by RT

n = PV /RT

The moles of NH3

n= (1.50 atm x 12.5 L) /( 0.0821 L. atm /mol.k x 298 K) =0.766 moles

The moles of O2

=(1.1 atm x 18.9 L) / ( 0.0821 L. atm/ mol.k x 323 K) = 0.784 moles

write the reaction between NH3 and O2

4 NH3 + 5 O2 →4 No +6H2O

from equation above 0.766 moles of NH3 reacted to produce

0.766 x 6/4 =1.149 moles of H2O

0.784 moles of O2 reacted to produce 0.784 x 6/5=0.9408 moles of H20

since O2 is totally consumed, O2 is the limiting reagent and therefore the moles of H2O produced= 0.9408 moles

mass of H2O = moles x molar mass

from periodic table the molar mass of H2O = (1 x2)+16= 18 g/mol

mass = 18 g/mol x 0.9408 moles= 16.93 grams

3 0

3 years ago

What is the correct prefix for 3 tri- di- mono- tetra-

Ivenika [448]

Answer:

tri-

Explanation:

Examples could be Tri-angle, Tri-cycle, Tri-ceratops

5 0

2 years ago

Read 2 more answers

In this experiment you will create solutions with different ratios of ethanol and water. What is the mole fraction of ethanol wh

Andrej [43]

Answer:

The mole fraction of ethanol is 0.6. A 10 mL volumetric pipette must be used for to measure the 10 mL of ethanol. The vessel should be clean and purged.

Explanation:

For calculating mole fraction of ethanol, the amount of moles ethanol must be calculated. Using ethanol density (0.778 g/mL), 10 mL of ethanol equals to 7.89 g of ethanol and in turn 0.17 moles of ethanol. The same way for calculate the amount of water moles (ethanol density=0.997 g/mL). 2 mL of water correspond to 0.11. The total moles are: 0.17+0.11=0.28. Mole fraction alcohol is: 0.17/0.28=0.6

5 0

3 years ago