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Nastasia [14]
3 years ago
13

A student weighs out a 6.64 g sample of , transfers it to a 500. mL volumetric flask, adds enough water to dissolve it and then

adds water to the 500. mL tick mark. What is the molarity of cobalt(II) fluoride in the resulting solution
Chemistry
1 answer:
Vsevolod [243]3 years ago
7 0

Answer:

the molarity of cobalt(II) fluoride in the resulting solution is = 0.137  M

Explanation:

Given that :

a student dissolves 6.64 g of CoF₂  into 500 mL of water

volume of the solution(water) = 500 mL = 0.50 L

The standard  molar mass of CoF₂ is 96.93 g/mol

number of moles of CoF₂ = mass of CoF₂/molar mass of CoF₂

number of moles of CoF₂ = 6.64 g/96.93 g/mol

number of moles of CoF₂ = 0.0685 mol

The molarity of any given substance is known to be as the number of moles of solute dissolved in one litre of solution.

Thus ;

Molarity of  cobalt(II) fluoride CoF₂ in the resulting solution is = number of moles / Volume in (L)

Molarity of  cobalt(II) fluoride CoF₂  = 0.0685 mol/ 0.50 L

= 0.137  M

Thus ; the molarity of cobalt(II) fluoride in the resulting solution is = 0.137  M

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Calculate the theoretical value for the number of moles of CO2 that should have been produced in each balloon assuming that 1.45
musickatia [10]

Answer:

For 1 antacid tablet (in ballon1) we get .0173 moles of CO2

for 2 tablets (in balloon 2) we get: 2*0,0173=  0.0346 moles of CO2

For 3 tablets (in balloon 3) we get 3* 0.0173 = 0.0519 moles of CO2

Explanation:

The complete question:

Calculate the theoretical value for the number of moles of CO2 that should have been produced in each balloon assuming that 1.45 g of NaHCO3 is present in an antacid tablet. Use stoichiometry (a mole ratio conversion must be present) to find your answers (there should be three: one answer for each balloon).

Balloon 1 had 1 antacid tab

Baloon 2 had 2

Balloon 3 had 3

Step 1: Data given

1.45 g of NaHCO3 is present in an antacid tablet

Molar mass of NaHCO3 = 84.00 g/mol

Step 2: The balanced equation

NaHCO3 + H2O → NaOH + H2O + CO2

Step 3: Calculate moles of NaHCO3

Moles NaHCO3 = mass NaHCO3 / molar mass NaHCO3

1.45g / 84.0 g/mol = .0173 moles

Step 4: Calculate moles CO2

For 1 mol NaHCO3 we need 1 mol H2O to produce 1 mol NaOH 1 mol H2O and 1 mol CO2

For 0.0173 moles NaHCO3 we'll get 0.0173 moles CO2

so for 1 antacid tablet we get .0173 moles of CO2

for 2 tablets we get: 2*0,0173 =  0.0346 moles of CO2

For 3 tablets we get 3* 0.0173 = 0.0519 moles of CO2

 

5 0
3 years ago
Be sure to answer all parts. In the average adult male, the residual volume (RV) of the lungs, the volume of air remaining after
Alenkinab [10]

<u>Answer:</u>

<u>For a:</u> The number of moles of air present in the RV is 0.047 moles

<u>For b:</u> The number of molecules of gas is 2.83\times 10^{22}

<u>Explanation:</u>

  • <u>For a:</u>

To calculate the number of moles, we use the equation given by ideal gas follows:

PV=nRT

where,

P = pressure of the air = 1.00 atm

V = Volume of the air = 1200 mL = 1.2 L    (Conversion factor:  1 L = 1000 mL)

T = Temperature of the air = 37^oC=[37+273]K=310K

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

n = number of moles of air = ?

Putting values in above equation, we get:

1.00atm\times 1.2L=n_{air}\times 0.0821\text{ L atm }mol^{-1}K^{-1}\times 310K\\n_{air}=\frac{1.00\times 1.2}{0.0821\times 310}=0.047mol

Hence, the number of moles of air present in the RV is 0.047 moles

  • <u>For b:</u>

According to mole concept:

1 mole of a compound contains 6.022\times 10^{23} number of molecules.

So, 0.047 moles of air will contain (0.047\times 6.022\times 10^{23})=2.83\times 10^{22} number of gas molecules.

Hence, the number of molecules of gas is 2.83\times 10^{22}

7 0
3 years ago
Eukaryotic plant and animal cells each have distinguishing characteristics. For example, plant cells have cell walls, while anim
kolezko [41]

Answer: well the answer is a

Explanation: how because I did that

3 0
3 years ago
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How does increasing temperature increase the number of reactions?
antiseptic1488 [7]

Answer:

Increasing the temperature increases reaction rates because of the disproportionately large increase in the number of high energy collisions. It is only these collisions (possessing at least the activation energy for the reaction) which result in a reaction

Explanation:

7 0
3 years ago
Which is the best practice recommended in the safety video to mix and acid or a base with a solvent?
Vesna [10]

Answer:

Never pour water into acid but acid into water

Explanation:

If water is poured into extremely concentrated acid/bases, the rate of volatility and exothermic reaction is too rapid and might cause a chemical eruption, leading to acid burns.

Safety precautions hence dictate the reverse is practiced.

I believe this is a clear answer.

4 0
3 years ago
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