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Harlamova29_29 [7]
3 years ago
5

Element (20X) in the periodic table exist in:

Chemistry
1 answer:
nikdorinn [45]3 years ago
3 0

It occurs in oxygen I think

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consider an exceptionally weak acid, HA, with Ka= 1 x 10-20. you make 0.1M solution of the salt NA. what is the pH.
iogann1982 [59]

Answer:

pH=10.5

Explanation:

Hello,

In this case, the dissociation of the given weak acid is:

HA\rightleftharpoons H^++A^-

Therefore, the law of mass action for it turns out:

Ka=\frac{[H^+][A^-]}{[HA]}

That in terms of the change x due to the reaction extent is:

1x10^{-23}=\frac{x*x}{0.1-x}

Thus, by solving with the quadratic equation or solver, we obtain:

x=31.6x10^{-12}M

Which clearly matches with the hydrogen concentration in the solution, therefore, the pH is:

pH=-log(-31.6x10^{-12})\\pH=10.5

Regards.

5 0
3 years ago
If 4.00 g of NaCl react with 10.00 g of AgNO3, what is the excess reactant?
Mekhanik [1.2K]
The reaction formula of this is NaCl + AgNO3 = NaNO3 + AgCl. The mole number of NaCl is 4/58.5=0.068 mol. The mole number of AgNO3 is 10/170=0.059 mol. So the NaCl is excess.
7 0
3 years ago
Read 2 more answers
How does carbon (C) differ from silicon (Si)?
steposvetlana [31]

Explanation:

carbon has 1 less electron energy shell than silicon

8 0
3 years ago
Two or more different elements chemically combine to form compounds.<br><br> True or false
vodomira [7]

Answer:

true

Explanation:

8 0
3 years ago
Estimate ΔH for the reaction using bond dissociation energies from Table 7.1. Give your answer in kcal. C6H12O6 has five C−C bon
Nat2105 [25]

The equation for the photosynthesis reaction in which carbon dioxide and water react to form glucose is . The hear reaction is the difference between the bond dissociation energies in the products and the bond dissociation energies of the reactants

 

The reactant molecules have 12 C = O, 12 H - O bonds while the product molecules have 5 C - C, 7 C – O, 5 H – O, and 6 O = O bonds. The average bond dissociation energies for the bonds involved in the reaction are 191 for C = O, 112 for H – O, 83 C –C, 99 C – H, 86 C – O, 119 O = O.

 

Substitute the average bond dissociation energies in the equation for and calculate as follows

= [12 (C=O) + 12 (H-O)] – [5(C-C) + 7(C-H) + 7 (C-O) + 5(H-O) + 6(O=O)]

= [12x191 kcal/mol + 12x112 kcal//mol] – [5x83 kcal/mol + 7x99 kcal/mol + 7x86 kcal/mol + 5x112 kcal/mol + 6x119 kcal/mol]

= 3636 kcal/mol – 2984 kcal/mol = 652 kcal/mol x 4.184 Kj/1kcal = 2.73x10^3 kJ/mol

 

So, enthalpy change for the reaction is 652 kcal/mol or 2.73x10^3 kJ/mol

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5 0
3 years ago
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