0.408 grams to moles

When we have to do a buffer solution we always have to choose the reaction that has the pKa closer to the desired pH value. When we find the pKa values we will obtain:

$pKa_1=-Log[6.9x10^-^3]=2.16$

$pKa_2=-Log[6.2x10^-^8]=7.20$

$pKa_3=-Log[4.8x10^-^13]=12.31$

The closer value is pKa2 with a value of 7.2. Therefore we have to use the second reaction. In which $H_2PO_4^-^1$ is the acid and $HPO_4^-^2$ is the base. Therefore the answer for the first question is B and the answer for the second question is C.

8 0

2 years ago

The Doppler effect changes the

dem82 [27]

A) Frequency due to motion

As you are moving toward the object that is making the sound the frequency is higher. When you begin to move away the frequency lowers.

3 0

3 years ago

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Composition of the nuclei of two atomic species A and B are given below:

Inessa [10]

Explanation:

(a) mass number = atomic number + number of neutrons

(the atomic number is the number of protons of an element)

mass number of A = 11 + 12 = 23

mass number of B = 17 + 18 = 35

(b) +1 and -1, respectively

(c) A+ + B- → AB (the first plus sign and the minus sign are superscripts)

5 0

2 years ago