Ask question

Ask question

All categories

3 years ago

5

Magnesium has three naturally occurring isotopes with masses of 23.99, 24.99, and 25.98 amu and natural abundances of 78.99%, 10

.00%, and 11.01%, respectively. calculate the atomic mass of magnesium.

1 answer:

Darya [45]3 years ago

5 0

Atomic mass of magnesium = (23.99 x 78.99%) + (24.99 x 10.00%) + (25.98 x 11.01%)
= 24.31 g/mol

You might be interested in

In liquids, the attractive intermolecular forces are ________. In liquids, the attractive intermolecular forces are ________. st

Fantom [35]

Answer:

strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each other.

Explanation:

In liquids, the attractive intermolecular forces are <u>strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each other</u>.

Intermolecular forces are the forces of repulsion or attraction.

Intermolecular forces lie between atoms, molecules, or ions. Intramolecular forces are strong in comparison to these forces.

<u />

5 0

2 years ago

Differentiate benzene and cyclohexane

slega [8]

<span>• Benzene has the formula of C6H<span>6 </span>whereas cyclohexane has the formula of C6H<span>12.
</span></span>
Benzene is an aromatic compound but cyclohexane is not aromatic.

Benzene is an unsaturated molecule, but cyclohexane is saturated.
<span>
Carbon atoms in the benzene ring have sp2 hybridization where carbon atoms in the cyclohexane have sp3 hybridization.</span>

Benzene has a planar structure whereas cyclohexane has chair conformations.<span>
</span>

5 0

2 years ago

A solution of phosphoric acid was made by dissolving 10.8 g of H3PO4 in 133.00 mL of water. The resulting volume was 137 mL. Cal

Nesterboy [21]

Answer:

Density is: 1.05 g/ml

Mole fraction solute: 0.015

Mole fraction solvent: 0.095

Molarity: 0.80 M

Molality: 0.82 m

Explanation:

A typical excersise of solution.

It is more confortable to make a table for this.

| masss | volume | mol

solute | | |

solvent | | |

solution | | |

Let's complete, what we have.

| masss | volume | mol

solute | 10.8g | |

solvent | | 133 mL |

solution | | 137 mL |

We can first, know how many moles are 10.8 g

Molar Mass H3PO4 = 97.99 g/mol

Mass / Molar mass = mol

10.8 g / 97.99 g/m = 0.110 mol

Density of water is 1 g/ml (it is a very knowly value)

From this data, we can know water mass, solvent.

Density = mass / volume

1 g/ml = mass / 133 mL

Mass = 133 g

We can also have the moles, by the molar mass of water 18 g/m

133 g / 18 g/m = 7.39 mol

| masss | volume | mol

solute | 10.8g | | 0.110 mol

solvent | 133g | 133 mL | 7.39 mol

solution | 143.8g | 137 mL | 7.50 mol

Mass of solution will be solute mass + solvent mass

Moles of solution will be solute moles + solvent moles

Now we can calculate everything.

Molarity means mol of solute in 1 L of solution. (mol/L)

We have to convert 137 mL in L (/1000)

0.137L so → 0.110 m / 0.137L = 0.80 M

Molality means mol of solute in 1kg of solvent.

We have to convert 133g in kg (/1000)

0.133 kg so → 0.110 m/0.133 kg = 0.82 m

Density is mass / volume

Solution density will be solution mass / solution volume

143.8 g/137 mL = 1.05 g/m

Molar fraction is : solute moles / total moles or solvent moles/total moles.

You can also (x 100%) to have a percent of them.

Remember sum of molar fraction = 1

Molar fraction of solute = 0.110 mol / 7.50mol = 0.015

Molar fraction of solvent = 7.39 mol / 7.50 mol = 0.985

5 0

2 years ago

The thermochemical equation for the reaction of carbon dioxide with sulfur dioxide is shown below. How can the reaction be descr

prisoha [69]

Answer: d. has high activation energy

Activation energy is the energy that a system requires to start a certain process. Also, it <u>is the minimum energy necessary for a given chemical reaction to occur</u>. For a reaction to occur between two molecules, they must collide in the correct orientation and have a minimum amount of energy equal to the activation energy.

As the molecules approach, their electron clouds repel, so energy is required for the collision to occur and therefore the reaction. The activation energy comes from the heat of the system, that is, the translational, vibrational energy, etc. of each molecule. However, if this energy is not enough, the reaction will not be spontaneous.

<u>A reaction between two molecules can be favored by supplying energy to the system.</u> In the case raised in the question, <u>energy equal to 1104 kJ is provided to the system to favor the next reaction </u>

CO2 (g) + 2SO2 (g) → CS2 (g) + 3O2 (g)

<u>Since the energy equal to 1104 kJ is included in the reactants, it can be deduced that it is the energy that is provided to the system for the reaction to occur. </u>However, from the value of this energy it can not be said whether the system is endothermic or exothermic since it is a kinetic variable and the variables of this type do not allow predicting the thermodynamic behavior of a system.

Furthermore, it can be seen that the value of this energy is considerably high, therefore the reaction described has a high activation energy.

3 0

2 years ago

The specific heat of zinc is 0.39 J/g*°C. How much energy needed to change the temperature of 34g of zinc from 22°C to 57°C. Is

Svetlanka [38]

Answer:

464.1 J absorbed.

Explanation:

Given data:

Specific heat of zinc = 0.39 J/g°C

Mass of zinc = 34 g

Temperature changes = 22°C to 57°C

Energy absorbed or released = ?

Solution:

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 57°C - 22°C

ΔT = 35°C

Q = m.c. ΔT

Q = 34 g. 0.39 J/g°C. 35°C

Q = 464.1 J

6 0

3 years ago