Simple Chem question

In a student experiment, the empirical formula of a copper halide was found by adding aluminum metal to an aqueous solution of t

Radda [10]

Answer: The empirical formula for the given compound is $CuCl_3$

Explanation:

We are given:

Mass of copper chloride in 1 L or 1000 mL of solution = 42.62 grams

Taking Trial A:

Volume of solution = 49.6 mL

Applying unitary method:

In 1000 mL of solution, the mass of copper chloride present is 42.62 grams

So, in 49.6 mL of solution, the mass of copper chloride will be = $\frac{42.62}{1000}\times 49.6=2.114g$

We are given:

Mass of filter paper = 0.908 g

Mass of filter paper + copper = 1.694 g

Mass of copper = [1.694 - 0.908] g = 0.786 g

Mass of chlorine in the sample = [2.114 - 0.786]g = 1.328 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Copper = $\frac{\text{Given mass of Copper}}{\text{Molar mass of Copper}}=\frac{0.786g}{63.5g/mole}=0.0124moles$

Moles of Chlorine = $\frac{\text{Given mass of Chlorine}}{\text{Molar mass of Chlorine}}=\frac{1.328g}{35.5g/mole}=0.0374moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.0124 moles.

For Copper = $\frac{0.0124}{0.0124}=1$

For Chlorine = $\frac{0.0374}{0.0124}=3.02\approx 3$

Step 3: Taking the mole ratio as their subscripts.

The ratio of Cu : Cl = 1 : 3

Hence, the empirical formula for the given compound is $CuCl_3$

3 0

3 years ago

When a solution of NaI reacts with a solution of AgNO3, what is the net ionic equation?

Leni [432]

Answer:

Ag⁺(aq) + I⁻(aq) → AgI(s)

Explanation:

Net ionic equation is a way to write a chemical equation in which you are listing only the species that are participating in the reaction.

In the reaction:

AgNO₃(aq) + NaI(aq) → AgI(s) + NaNO₃(aq).

The ionic equation is:

Ag⁺(aq) + NO₃⁻(aq) + Na⁺(aq) + I⁻(aq) → AgI(s) + Na⁺(aq) + NO₃⁻(aq).

Now, listing only the species that are participating in the reaction:

3 0

3 years ago

What are six forms of energy? Find an example of each.

Evgesh-ka [11]

1-Electric Energy
Example: A lightbulb is an example of electric energy
2-Sound Energy
Example: When a dog barks, that is sound energy
3-Solar Energy
Example: When we use the sun for energy. Like using it to dry our clothes.
4-Chemical Energy
Example: An example is a battery. That may not seem like it, but it is Chemical Energy.
5-Nuclear Energy
Example: A fission reaction at a nuclear powerplant
6-Thermal Energy
Example: A pot of water boiling on an Electric Stove
~Silver

4 0

3 years ago

4-hydroxypentanal reacts with one equivalent of methanol to form a cyclic acetal.

quester [9]

Answer:

Explanation:

The equation is given as:

CH3CHOHC2H4CHO + CH3OH --> CYCLIC ACETAL + H2O

This above equation is carried out in the presence of a strong acid. There are five mechanisms employed and they are:

Step 1:

Initial formation of the hemiacetal which takes several steps

Step 2:

Addition of a proton. The hemicetal is protonated on the hydroxyl group (-OH group)

Step 3:

As seen a bond is broken to give the H2O molecule and a resonance stabilized cation.

The carbonyl group on the cation is enriched with the oxygen-18 got from the H2O molecule as seen in the mechanism.

Step 4:

An attraction occurs between electrophile and nucleophile i.e the stabilised cation and the lone paids of the methanol.

Step 5:

Finally, a proton (+) is removed from the molecule by a lone pair of electron on the methanol.

Attached are the Steps 1 - 5 mechanism below

4 0

3 years ago

Potassium nitrate has a lattice energy of -163.8 kcal/mol and a heat of hydration of -155.5 kcal/mol.

Brut [27]

Answer:

293.99 g

OR

0.293 Kg

Explanation:

Given data:

Lattice energy of Potassium nitrate (KNO3) = -163.8 kcal/mol

Heat of hydration of KNO3 = -155.5 kcal/mol

Heat to absorb by KNO3 = 101kJ

To find:

Mass of KNO3 to dissolve in water = ?

Solution:

Heat of solution = Hydration energy - Lattice energy

= -155.5 -(-163.8)

= 8.3 kcal/mol

We already know,

1 kcal/mol = 4.184 kJ/mole

Therefore,

= 4.184 kJ/mol x 8.3 kcal/mol

= 34.73 kJ/mol

Now, 34.73 kJ of heat is absorbed when 1 mole of KNO3 is dissolved in water.

For 101 kJ of heat would be

= 101/34.73

= 2.908 moles of KNO3

Molar mass of KNO3 = 101.1 g/mole

Mass of KNO3 = Molar mass x moles

= 101.1 g/mole x 2.908

= 293.99 g

= 0.293 kg

293.99 g potassium nitrate has to dissolve in water to absorb 101 kJ of heat.

4 0

3 years ago

Simple Chem question - help!