Question 13 help i’m timed thx u r loved

5. Write a net ionic equation that occurs in a Na2HPO4/NaH2PO4 buffer solution when: A) a small amount of HCl is added (2 points

labwork [276]

Answer: (A) $H_{3}O^{+}(aq) + HPO^{2-}_{4}(aq) \rightarrow H_{2}PO^{2-}_{4}(aq) + H_{2}O(l)$

(B) $H_{2}PO^{-}_{4}(aq) + OH^{-}(aq) \rightarrow HPO^{2-}_{4}(aq) + H_{2}O(l)$

Explanation:

(A) As we know that HCl is a strong acid and when it is added to an aqueous solution then it leads to increase in the concentration of hydrogen ions. And, when an acid or base is added to a solution then any resistance by the solution in changing the pH of the solution is known as a buffer.

This means that addition of buffer into the given solution will not cause much change in the concentration of $H_{3}O^{+}$ in large amount.

As both the buffer components are salt then they will remain dissociated as follows.

$Na_{2}HPO_{4}(aq) \rightarrow 2Na^{+}(aq) + HPO^{2-}_{4}(aq)$

$NaH_{2}PO_{4}(aq) \rightarrow Na^{+}(aq) + H_{2}PO^{-}_{4}(aq)$

Hence, net ionic equation will be as follows.

$H_{3}O^{+}(aq) + HPO^{2-}_{4}(aq) \rightarrow H_{2}PO^{2-}_{4}(aq) + H_{2}O(l)$

(B) When we add small amount of sodium hydroxide into the solution then there will occur an increase in concentration of hydroxide ions into the solution. But then due to the presence of buffer there will occur not much change in concentration and the acid will get converted into salt.

$NaOH(aq) \rightarrow Na^{+}(aq) + OH^{-}(aq)$

The net ionic equation is as follows.

$H_{2}PO^{-}_{4}(aq) + OH^{-}(aq) \rightarrow HPO^{2-}_{4}(aq) + H_{2}O(l)$

7 0

3 years ago

Many bacteria cannot reproduce and cooler temperatures in our destroyed at high temperatures. How do you humans take advantage o

12345 [234]

freezer and refrigerator too cold for most bacteria to grow .oven too hot for bacteria to survive

3 0

3 years ago

A solution is prepared from 4.5701 g of magnesium chloride and 43.238 g of water. The vapor pressure of water above this solutio

balandron [24]

Answer:

i = 2.483

Explanation:

The vapour pressure lowering formula is:

Pₐ = Xₐ×P⁰ₐ (1)

For electrolytes:

Pₐ = nH₂O / (nH₂O + inMgCl₂)×P⁰ₐ

Where:

Pₐ is vapor pressure of solution (0.3624atm), nH₂O are moles of water, nMgCl₂ are moles of MgCl₂, i is Van't Hoff Factor, Xₐ is mole fraction of solvent and P⁰ₐ is pressure of pure solvent (0.3804atm)

4.5701g of MgCl₂ are:

4.5701g ₓ (1mol / 95.211g) = 0.048000 moles

43.238g of water are:

43.238g ₓ (1mol / 18.015g) = 2.400 moles

Replacing in (1):

0.3624atm = 2,4mol / (2.4mol + i*0.048mol)×0.3804atm

0.3624atm / 0.3804atm = 2,4mol / (2.4mol + i*0.048mol)

2.4mol + i*0.048mol = 2.4mol / 0.9527

2.4mol + i*0.048mol = 2.5192mol

i*0.048mol = 2.5192mol - 2.4mol

i = 0.1192mol / 0.048mol

i = 2.483

I hope it helps!

4 0

3 years ago

For the reaction NH4NO3 (s) → N2O (g) + 2H2O (l), you decompose 1 mole NH4NO3 and only get 0.75 moles of N2O. The percent yield

attashe74 [19]

Answer:

The answer to your question is False.

Explanation:

Data

1 mole of NH₄NO₃

0.75 moles of N₂O

Percent yield = 25%

Chemical reaction

NH₄NO₃ ⇒ N₂O + 2H₂O

Process

1.- Determine the theoretical yield

1 mol NH₄NO₃ ------------- 1 mol of N₂O

2.- Calculate the percent yield

Percent yield = Actual yield / Theoretical yield x 100

-Substitution

Percent yield = 0.75 / 1 x 100

-Simplification

Percent yield = 0.75 x 100

-Result

Percent yield = 75%

Conclusion

False, the actual percent yield is 75%

5 0

4 years ago

Which of the following molecules may diffuse freely through a phospholipid bilayer? (select two answers) asparagine, an amino ac

lisabon 2012 [21]

Answer:

testosterone, a steroid hormone

molecular oxygen (O₂)

Explanation:

Phospholipid Bi layer is permeable to some molecules and it will allow them to pass through it freely. Molecules which are soluble in water (polar molecules or hydrophillic molecules) are less permeable through phospholipid Bi layer . In given options Molecular Oxygen and Testosterone( steroid Hormone) are permeable through the layer because of its lipid solubility and size of the molecule .

3 0

3 years ago