What is the number of moles of potassium chloride present in 142 g of kcl?

How many lead (Pb) atoms are in a 5.32 g sample of pure lead?

Elanso [62]

Answer:

1.55×10²² molecules.

Explanation:

We'll begin by calculating the number of mole in 5.32 g of pure lead (Pb). This can be obtained as follow:

Mass of Pb = 5.32 g

Molar mass of Pb = 207 g/mol

Mole of Pb =?

Mole = mass /molar mass

Mole of Pb = 5.32/207

Mole of Pb = 0.0257 mole

Finally, we shall determine the number of molecules in 0.0257 mole of Pb. This can be obtained as follow:

From Avogadro's hypothesis,

I mole of Pb contains 6.02×10²³ molecules.

Therefore, 0.0257 mole will contain = 0.0257 × 6.02×10²³ = 1.55×10²² molecules.

Therefore, 5.32 g of pure lead (Pb) contains 1.55×10²² molecules.

4 0

3 years ago

I. define ionic bonding and describe how it can be formed between sodium and chlorine

Vitek1552 [10]

Math or whatever thing

6 0

3 years ago

400. mg of an unknown protein are dissolved in enough solvent to make 5.00 mL of solution. The osmotic pressure of this solution

ch4aika [34]

Answer: The molecular weight of protein is $1.14\times 10^2g/mol$

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iMRT$

or,

$\pi=i\times \frac{m_{solute}\times 1000}{M_{solute}\times V_{solution}\text{ (in mL)}}}\times RT$

where,

$\pi$ = Osmotic pressure of the solution = 0.0861 atm

i = Van't hoff factor = 1 (for non-electrolytes)

$m_{solute}$ = mass of protein = 400 mg = 0.4 g (Conversion factor: 1 g = 1000 mg)

$M_{solute}$ = molar mass of protein = ?

$V_{solution}$ = Volume of solution = 5.00 mL

R = Gas constant = $0.0821\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the solution = $25^oC=[25+273]K=298K$

Putting values in above equation, we get:

$0.0861atm=1\times \frac{0.4g\times 1000}{M\times 100}\times 0.0821\text{ L. atm }mol^{-1}K^{-1}\times 298K\\\\M=1136.62g/mol=1.14\times 10^2g/mol$

Hence, the molecular weight of protein is $1.14\times 10^2g/mol$

4 0

3 years ago

When C2H6(g) reacts with O2(g) according to the following reaction, 1.43×103 kJ of energy are evolved for each mole of C2H6(g) t

dezoksy [38]

Answer:

-2.86x10³ kJ

Explanation:

The enthalpy of a reaction (ΔH) is defined as the heat produced or consumed by a reaction. In the reaction:

2 C₂H₆(g) + 7 O₂(g) → 4 CO₂(g) + 6 H₂O(g)

The ΔH is the heat envolved in the reaction per 2 moles of C₂H₆. 1.43x10³ kJ are involved when 1 mole reacts. Thus, when 2 moles react, involved heat is:

1.43x10³ kJ ₓ 2 = 2.86x10³ kJ. As the reaction is a combustion reaction (Produce CO₂ and H₂O), the heat involved in the reaction is PRODUCED, that means ΔH is negative, -2.86x10³ kJ

8 0

3 years ago

Write the net ionic equation for the acid-base hydrolysis equilibrium that is established when ammonium perchlorate is dissolved

Whitepunk [10]

Answer: The net ionic equation is written below.

Explanation:

Net ionic equation of any reaction does not include any spectator ions.

Spectator ions are defined as the ions which do not get involved in the chemical equation. It is also defined as the ions which are found on both the sides of the chemical reaction when it is present in ionic form.

The chemical equation for the reaction of ammonium perchlorate and water is given as:

$NH_4ClO_4(aq.)+H_2O(l)\rightarrow NH_4OH(aq.)+HClO_4(aq.)$

Ionic form of the above equation follows:

$NH_4^+(aq.)+ClO_4^-(aq.)+H_2O(l)\rightarrow NH_4OH(aq.)+H^+(aq.)+ClO_4^-(aq.)$

Ammonium hydroxide will not dissociate into its ions because it is a weak base.

As, chlorate ions are present on both the sides of the reaction, thus, it will not be present in the net ionic equation.

The net ionic equation for the above reaction follows:

$NH_4^+(aq.)+H_2O(l)\rightarrow NH_3^+(aq.)+H_3O^+(aq.)$

Hence, the net ionic equation is given above.

5 0

3 years ago