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True [87]
3 years ago
7

Why is it important to mark the solvent front immediately

Chemistry
1 answer:
vodka [1.7K]3 years ago
8 0

It is important to make sure the solvent is level and not at an angle so you do not get an angled solvent front.

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A sample of krypton gas collected at a pressure of 1.31 atm and a temperature of 26.0°C is found to occupy a volume of 23.3 lite
djyliett [7]

Mol of Kr gas = 1.244

<h3>Further explanation</h3>

In general, the gas equation can be written  

<h3> PV=nRT </h3>

where  

P = pressure, atm  

V = volume, liter  

n = number of moles  

R = gas constant = 0.08205 L.atm / mol K  

T = temperature, Kelvin  

P=1.31 atm

V=23.3 L

T=26+273=299 K

mol of sample :

\tt n=\dfrac{PV}{RT}=\dfrac{1.31\times 23.3}{0.08205\times 299}=1.244

3 0
3 years ago
Two chemical samples were heated individually in a flame and both produced an identical orange flame. What conclusion can you dr
cestrela7 [59]

Answer: they both contain the same metal(calcium)

Explanation: calcium burns with a characteristic orange color.

6 0
4 years ago
1. A student is examining a cell through a microscope. She notes the
Hoochie [10]
C

Animal cells do not have cell walls or chloroplasts!
3 0
3 years ago
What are the concentrations of A , A, B , B, and C C at equilibrium if, at the beginning of the reaction, their concentrations a
Elenna [48]

The question is incomplete, here is the complete question:

A reaction

A+B\rightleftharpoons C

has a standard free-energy change of -4.88 kJ/mol at 25°C

What are the concentrations of A, B, and C at equilibrium if at the beginning of the reaction their concentrations are 0.30 M, 0.40 M and 0 M respectively?

<u>Answer:</u> The equilibrium concentrations of A, B and C are 0.117 M, 0.217 M, 0.183 M respectively.

<u>Explanation:</u>

Relation between standard Gibbs free energy and equilibrium constant follows:

\Delta G^o=-RT\ln K_c

where,

\Delta G^o = Standard Gibbs free energy = -4.88 kJ/mol = -4880 J/mol  (Conversion factor: 1 kJ = 1000 J)

R = Gas constant = 8.314J/K mol

T = temperature = 25^oC=[273+25]K=298K

K_c = equilibrium constant of the reaction

Putting values in above equation, we get:

-4880J/mol=-(8.3145J/Kmol)\times 298K\times \ln K_c\\\\K_c=7.17

We are given:

Initial concentration of A = 0.30 M

Initial concentration of B = 0.40 M

Initial concentration of C = 0 M

The chemical reaction follows:

                               A+B\rightleftharpoons C

<u>Initial:</u>                 0.30  0.40      0

<u>At eqllm:</u>         0.30-x   0.40-x    x

The expression of equilibrium constant for the above reaction follows:

K_c=\frac{[C]}{[A][B]}

We are given:

K_c=7.17

Putting values in above equation, we get:

7.17=\frac{x}{(0.30-x)\times (0.40-x)}\\\\x=0.183,0.657

Neglecting the value of x = 0.657, because change cannot be greater than the initial concentration

So, equilibrium concentration of A = (0.30-x)=(0.30-0.183)=0.117M

Equilibrium concentration of B = (0.40-x)=(0.40-0.183)=0.217M

Equilibrium concentration of C = x=0.183M

Hence, the equilibrium concentrations of A, B and C are 0.117 M, 0.217 M, 0.183 M respectively.

5 0
3 years ago
How do you convert 134kj to Calories?
Sonja [21]
1 kilo joule = 0.239006 calories
134 kilo joule = 134 x 0.239006
                      = 32.026804 calories
5 0
3 years ago
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