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Assoli18 [71]
3 years ago
9

What is the pH of a mixture of 0.042 M NaH2PO4 and 0.058 M Na2HPO4? Hint: The pKa of phosphate is 6.86.

Chemistry
1 answer:
AlekseyPX3 years ago
5 0

Answer:

The pH value of the mixture will be 7.00

Explanation:

Mono and disodium hydrogen phosphate mixture act as a buffer to maintain pH value around 7. Henderson–Hasselbalch equation is used to determine the pH value of a buffer mixture, which is mathematically expressed as,

pH=pK_{a} + log(\frac{[Base]}{[Acid]})

According to the given conditions, the equation will become as follow

pH=pK_{a} + log(\frac{[Na_{2}HPO_{4} ]}{[NaH_{2}PO_{4}]})

The base and acid are assigned by observing the pKa values of both the compounds; smaller value means more acidic. NaH₂PO₄ has a pKa value of 6.86, while Na₂HPO₄ has a pKa value of 12.32 (not given, but it's a constant). Another more easy way is to the count the acidic hydrogen in the molecular formula; the compound with more acidic hydrogens will be assigned acidic and vice versa.

Placing all the given data we obtain,

pH=6.86 + log(\frac{0.058}{0.042})

pH=7.00

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If the graph of y = a x 2 + b x + c does not intersect the x -axis, then what is true about the roots? Both are real roots. Both
Reptile [31]

Answer:

Both roots are imaginary roots.

Explanation:

Consider these things:

If we try to solve x²+1 = 0, notice that we aren't able to solve the equation in Real Number system because there are no negative outputs for quadratic function.

Remember that quadratic function has range greater or equal to the max-min value.

x-axis plane represents the solutions of that equation. If a graph intersects x-axis plane then it has a solution.

While a graph that doesn't have any intersects on x-plane, it means that the equation for that graph doesn't have real solutions but imaginary solutions.

As you may notice some of parabola graph has one intersect, two intersects or none. One intersect is one solution to the equation — Two intersects are two solutions of the equation and lastly, no intersects mean that no real solutions and remain only imaginary solution.

8 0
2 years ago
Find mass of 3 moles of water​
EleoNora [17]

Answer:

54 g

Explanation:

1 mole of water = H2O

mass of 1 mole of H2O= mass of h2 + mass of o

= 2× mass of h +mass of o

= 2×1+16 =18 g

1 mole of water = 18g

3moles of water = 18×3g= 54g

6 0
3 years ago
The following thermochemical equation is for the reaction of nitrogen(g) with oxygen(g) to form nitrogen dioxide(g). N2(g) + 2O2
Rzqust [24]

<u>Answer:</u> The mass of nitrogen gas reacted to produce given amount of energy is 5.99 grams.

<u>Explanation:</u>

The given chemical reaction follows:

N_2(g)+2O_2(g)\rightarrow 2NO_2(g);\Delta H=66.4kJ

We know that:

Molar mass of nitrogen gas = 28 g/mol

We are given:

Enthalpy change of the reaction = 14.2 kJ

To calculate the mass of nitrogen gas reacted, we use unitary method:

When enthalpy change of the reaction is 66.4 kJ, the mass of nitrogen gas reacted is 28 grams.

So, when enthalpy change of the reaction is 14.2 kJ, the mass of nitrogen gas reacted will be = \frac{28}{66.4}\times 14.2=5.99g

Hence, the mass of nitrogen gas reacted to produce given amount of energy is 5.99 grams.

8 0
3 years ago
CH3OCH3 (ether) will dissolve in water because
dangina [55]

Answer:

a. polar solutes dissolve in polar solvents.

Explanation:

Polarity is a phenomenon that has to do with the positive and negative electric (ionic) charges of a molecule. A molecule with distinct positive and electric charge is said to be POLAR. However, water is said to be a universal solvent because it dissolves more substances than any other solvent can.

This solvent property of water is a function of its POLARITY. Polar solutes dissolve in polar solvents. Hence, only polar solutes can dissolve in water (a polar solvent). Hence, in this case, CH3OCH3 (ether) will dissolve in water because it is a POLAR molecule/solute.

5 0
3 years ago
How many moles are in 25 g KMnO4
Ronch [10]

Answer:

0.158 moles KMnO4

Explanation:

According to the Periodic Table,

K = 39.10 g/mol

Mn = 54.94 g/mol

O = 16.00 g/mol

KMnO4 = 39.10 g/mol + 54.94 g/mol + 4(16.00 g/mol) = 158.04 g/mol

25.0 grams KMnO4              1 mole

-----------------------------  x --------------------------  = 0.158 moles KMnO4

                                          158.04 grams

8 0
3 years ago
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