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saveliy_v [14]
3 years ago
10

Consultați sistemul periodic și aranjați în ordinea creșterii caracterului nemetalic următoarele elemente:

Chemistry
1 answer:
lukranit [14]3 years ago
7 0
I’m sorry I just really need points rn I love you
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What is the ph of a soft drink in which the major buffer ingredients are 6.6 g of nah2po4 and 8.0 g of na2hpo4 per 355 ml of sol
Alex777 [14]
The Relative Formula Mass of NaH2PO4 is 120 g/mol
Therefore, the number of moles = 6.6/120
                                                   = 0.055 moles of NaH2PO4 which is also equal to the number of moles of H2PO4.
[H2PO4-] = Number of moles oof H2PO4-/Volume of the solution in L
  = 0.055/ ( 355 ×10^-3)
  = 0.155 M
Na2HPO4 undergoes complete dissociation as follows;
Na2HPO4 (aq)= 2Na+ (aq) + HPO4^2- (aq)

1 mole of Na2HPO4 = 142 g/mol
Therefore; number of moles = 8.0/142
                                             = 0.0563 moles
 [HPO4 ^-2] is given by no of moles HPO4^2- /volume of the solution in L
     = 0.0563/(355×10^-3)
     =  0.1586 M
Both H2PO4^2- and HPO4^2- are weak acids the undergoes partial dissociation 
Ka of H2PO4- = 6.20 × 10^-8
 [H+] =Ka*([H2PO4-]/[HPO4(2-)]
        = (6.20 ×10^-8)×(0.155/0.1586)
        = 6.059 ×10^-8 M
pH = - log[H+]
     = - log (6.059×10^-8)
     = 7.218

5 0
3 years ago
Which term best describes the role of hydrogen gas in the formation of a water molecule?
Alex Ar [27]
I believe the correct answer from the choices listed above is the last option. The term that would best describe the <span>role of hydrogen gas in the formation of a water molecule would be a reactant. Water has a formula of H2O where it contains water so it should be  that hydrogen is a reactant. </span>
7 0
3 years ago
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What atomic component contributes to many of the trends of elements
aivan3 [116]

what??? i need more information

3 0
3 years ago
Match the symbol for each element with the name of the element. 1. hydrogen K 2. helium Mg 3. sodium He 4. magnesium H 5. potass
insens350 [35]

Answer:

1. hydrogen - H

2. helium - He

3. sodium - Na

4. magnesium - Mg

5. potassium - K

Explanation:

Hydrogen is the element of group 1 and first period. The atomic number of hydrogen is 1 and the symbol of the element is H.

The electronic configuration of the element hydrogen is:-

1s^1

Helium is the element of group 18 and first period. The atomic number of helium is 2 and the symbol of the element is He.

The electronic configuration of the element helium is:-

1s^2

Sodium is the element of group 1 and third period. The atomic number of sodium is 11 and the symbol of the element is Na.

The electronic configuration of the element sodium is:-

1s^22s^22p^63s^1

Magnesium is the element of group 2 and third period. The atomic number of magnesium is 12 and the symbol of the element is Mg.

The electronic configuration of the element magnesium is:-

1s^22s^22p^63s^2

Potassium is the element of group 1 and forth period. The atomic number of potassium is 19 and the symbol of the element is K.

The electronic configuration of the element potassium is:-

1s^22s^22p^63s^23p^64s^1

5 0
3 years ago
Match each scientist to their discovery regarding the atom
neonofarm [45]

Answer:

Thomson--atoms cotain electron

Ernest Rutherford--atoms have a positive nucleus

R.A Millikan--electrons have Q=-1

Dalton--atoms are indivisible

3 0
3 years ago
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