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zepelin [54]
3 years ago
15

How many water molecules does it contain? The density of water is 1.0 g/cm3.

Chemistry
1 answer:
max2010maxim [7]3 years ago
6 0

Complete question is;

A drop of water has a volume of approximately 7 × 10⁻² ml. How many water molecules does it contain? The density of water is 1.0 g/cm³.

This question will require us to first find the number of moles and then use avogadro's number to get the number of water molecules.

<em><u>Number of water molecules = 2.34 × 10²¹ molecules</u></em>

We are given;

Volume of water; V = 7 × 10⁻² ml

Density of water; ρ = 1 g/cm³ = 1 g/ml

Formula for mass is; m = ρV

m = 1 × 7 × 10⁻²

m = 7 × 10⁻² g

from online calculation, molar mass of water = 18.01 g/mol

Number of moles(n) = mass/molar mass

Thus;

n = (7 × 10⁻²)/18.01

n = 3.887 × 10⁻³ mol

from avogadro's number, we know that;

1 mol = 6.022 × 10²³ molecules

Thus,3.887 × 10⁻³ mol will give; 6.022 × 10²³ × 3.887 × 10⁻³ = 2.34 × 10²¹ molecules

Read more at; brainly.in/question/17990661

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In order for a process to be spontaneous, Multiple Choice the entropy of the surroundings must increase. the entropy of the surr
Crazy boy [7]

Answer:

The correct answer is entropy change of the surrounding plus the entropy change of the system must be positive.

Explanation:

The term entropy is a state function.Entropy can be defined as the disorder or randomness of the molecules in a system.

 A spontaneous reaction is a type of reaction which deals with the release of free energy.The change of free energy in case of spontaneous reaction is always negative.

 According to the second law of thermodynamics a spontaneous reaction will occur in a system if the total entropy of both  system and surrounding increases during the reaction.

8 0
3 years ago
As with other ionic compounds, potassium bromate, KBrO3, dissociates into ions when it dissolves in water. If 13.8 g of KBrO3 is
chubhunter [2.5K]

Answer:

ΔH of dissociation is 38,0 kJ/mol

Explanation:

The dissociation reaction of KBrO₃ is:

<em>KBrO₃ → K⁺ + BrO₃⁻ </em>

This dissolution consume heat that is evidenced with the decrease in water temperature.

The heat consumed is:

q = CΔTm

Where C is specific heat of water (4,186 J/mol°C)

ΔT is the temperature changing (18,0°C - 13,0°C = 5,0°C)

And m is mass of water (150,0 mL ≈ 150,0 g)

Replacing, heat consumed is:

q = 3139,5 J ≡ 3,14 kJ

13,8 g of KBrO₃ are:

13,8 g×(1mol/167g) = 0,0826 moles

Thus, ΔH of dissociation is:

3,14kJ / 0,0826mol = <em>38,0 kJ/mol</em>

<em></em>

I hope it helps!

3 0
3 years ago
A generic weak acid with formula HA has a Ka = 2.76 x 10-8. Calculate the Kb for the conjugate base of the acid.
Reika [66]

Answer:

3.62x10⁻⁷ = Kb

Explanation:

The acid equilibrium of a weak acid, HX, is:

HX + H₂O ⇄ X⁻ + H₃O⁺

Where Ka = [X⁻] [H₃O⁺] / [HX]

And basic equilibrium of the conjugate base, is:

X⁻ + H₂O ⇄ OH⁻ + HX

Where Kb = [OH⁻] [HX] / [X⁻]

To convert Ka to Kb we must use water equilibrium:

2H₂O ⇄ H₃O⁺ + OH⁻

Where Kw = 1x10⁻¹⁴ = [OH⁻] [H₃O⁺]

Thus, we can obtain:

Kw = Ka*Kb

Solving for Kb:

Kw / Ka = Kb

1x10⁻¹⁴ /  2.76x10⁻⁸ =

3.62x10⁻⁷ = Kb

4 0
3 years ago
If the rate of decomposition of ammonia, NH3, at 1150 K is 2.10 x 10-6 mol/L/s, what is the
Alina [70]

Answer:

3.15 × 10⁻⁶ mol H₂/L.s

1.05 × 10⁻⁶ mol N₂/L.s

Explanation:

Step 1: Write the balanced equation

2 NH₃ ⇒ 3 H₂ + N₂

Step 2: Calculate the rate of production of H₂

The molar ratio of NH₃ to H₂ is 2:3. Given the rate of decomposition of NH₃ is 2.10 × 10⁻⁶ mol/L.s, the rate of production of H₂ is:

2.10 × 10⁻⁶ mol NH₃/L.s × 3 mol H₂/2 mol NH₃ = 3.15 × 10⁻⁶ mol H₂/L.s

Step 3: Calculate the rate of production of N₂

The molar ratio of NH₃ to N₂ is 2:1. Given the rate of decomposition of NH₃ is 2.10 × 10⁻⁶ mol/L.s, the rate of production of N₂ is:

2.10 × 10⁻⁶ mol NH₃/L.s × 1 mol N₂/2 mol NH₃ = 1.05 × 10⁻⁶ mol N₂/L.s

3 0
3 years ago
How can cool red giant be more luminous than a warmer main sequence star?
ruslelena [56]

Answer: C

Explanation:

5 0
3 years ago
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