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zhannawk [14.2K]
3 years ago
12

How many moles are present in a 24.5 gram sample of K2Cr2O7?

Chemistry
1 answer:
attashe74 [19]3 years ago
6 0
The answer to this is solved through stochiometry: the answer is  this: 0.0833mol

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What is the percentage of water in the hydrate CoCl2 • 6H2O? Can someone help me with this one?
valkas [14]
Okay, to do this you have to work with the relative molecular mass (RMM). You can get this from looking at the periodic table.

The RMM for the whole molecule is:
58.933 + (2 x 35.453) + (12 x 1.008) + (6 x 15.9994) = 237.96

Then you work out the RMM for water:
(2 x 1.008) + 15.9994 = 18.0154

As there are 6 moles of water in this molecule then multiply the RMM of H2O by 6 = 108.0924

Finally, divide the total H2O RMM by the total molecule RMM and multiply by 100 to get a percentage:
(108.0925 / 237.96) x 100 = 45.42%
7 0
3 years ago
Can somebody help with parts c and d
Alecsey [184]

Answer:

13. Na  14. Ne. 15. U. 16. Ca. 17. C. l 18. O.  19. Cl. 20. Si  21. U  22. N.

23. Na 24. Ne. 25. U 26. Sc. 27. N 28. O 29. Cl 30. Si 31. U 32. N.

Explanation:

The general trend as you go to the right in any one period is for the size to decrease.

The general trend is that the size increases as you go down a Group.

The general trend as you go from the bottom left to the top right is a decrease in size.

Ionization energy increases as we move to the right in a period.

It decreases as we move down a group.

Going from the bottom left to top right - the ionization increases.

6 0
3 years ago
In a aqueous solution of 4-chlorobutanoic acid , what is the percentage of -chlorobutanoic acid that is dissociated
lord [1]

Answer:

Explanation:

Let assume that the missing aqueous solution of 4-chlorobutanoic acid = 0.76 M

Then, the dissociation of 4-chlorobutanoic acid can be expressed as:

\mathsf{C_3H_6ClCO_2H }          ⇄      \mathsf{C_3H_6ClCO_2^-}      +      \mathsf{H^+}

The ICE table can be computed as:

                   \mathsf{C_3H_6ClCO_2H }          ⇄      \mathsf{C_3H_6ClCO_2^-}      +      \mathsf{H^+}

Initial              0.76                                 -                           -

Change            -x                                  +x                         +x

Equilibrium   0.76 - x                              x                          x  

K_a = \dfrac{[\mathsf{C_3H_6ClCO_2^-}] [\mathsf{H^+}]}{\mathsf{[C_3H_6ClCO_2H ]}}

K_a = \dfrac{[x] [x]}{ [0.76-x]}

where:

K_a = 3.02*10^{-5}

3.02*10^{-5} = \dfrac{x^2}{ [0.76-x]}

however, the value of x is so negligible:

0.76 -x = 0.76

Then:

3.02*10^{-5}*0.76 = x^2

x=\sqrt{3.02*10^{-5}*0.76 }

x = 0.00479 M

∴

x = \mathsf{[C_3H_6ClCO_2^-] = [H^+]=} 0.00479 M

\mathsf{C_3H_6ClCO_2H }  = (0.76 - 0.00479) M

= 0.75521 M

Finally, the percentage of the acid dissociated is;

= ( 0.00479 / 0.76) × 100

= 0.630 M

7 0
3 years ago
Q1... list ten metal ..?​
Roman55 [17]

Gold.

Silver.

Iron.

Copper.

Nickel.

Aluminum.

Mercury( Liquid metal)

Titanium.

7 0
3 years ago
Read 2 more answers
Which of the following conditions indicate a basic solution at 25°C?
gladu [14]

Answer:

B. , C.  and D.

Explanation:

pH is defined as the negative logarithm of the concentration of hydrogen ions.

Thus,  

pH = - log [H⁺]

pH scale generally runs from 1 to 14 where pH = 7 represents neutral medium, pH < 7 represents acidic medium and pH > 7 represents basic medium.

Also, pH + pOH = 14  

(a) So, pOH = 11.21

pH = 14 - 11.21 = 2.79

The solution is acidic.

(b) pH = 9.42

The solution is basic.

c. [OH⁻] > [H⁺]

More concentration of hydroxide ions leads to basic solution.

d. [OH⁻]> 1.0 x 10⁻⁷ M

1.0 x 10⁻⁷ M leads to neutral solution and hydroxide ions concentration greater than this yields to basic solution.

5 0
4 years ago
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