Answer is: A. test and determine the pH values of unknown solutions.
Acid-base indicators are usually weak acids or bases and they are chemical detectors for hydrogen or hydronium cations (pH or pOH values).
Example for acid-base indicator is phenolphthalein (molecular formula C₂₀H₁₄O₄). Phenolphthalein is colorless in acidic solutions and pink in basic solutions.
Another example is methyl orange. It is red colour in acidic solutions and yellow colour in basic solutions.
Answer:
Explanation:
Molar mass of NaCl = (23+35.5)
Molar mass of NaCl = 58.5g/mol
Molar mass of C12H22011
= 12(12) + 22(1) + 16(11)
= 144 +22 + 176
= 342g/mol
Answer:
a. Kp=1.4


b.Kp=2.0 * 10^-4


c.Kp=2.0 * 10^5


Explanation:
For the reaction
A(g)⇌2B(g)
Kp is defined as:

The conditions in the system are:
A B
initial 0 1 atm
equilibrium x 1atm-2x
At the beginning, we don’t have any A in the system, so B starts to react to produce A until the system reaches the equilibrium producing x amount of A. From the stoichiometric relationship in the reaction we get that to produce x amount of A we need to 2x amount of B so in the equilibrium we will have 1 atm – 2x of B, as it is showed in the table.
Replacing these values in the expression for Kp we get:

Working with this equation:

This last expression is quadratic expression with a=4, b=-(4+Kp) and c=1
The general expression to solve these kinds of equations is:
(equation 1)
We just take the positive values from the solution since negative partial pressures don´t make physical sense.
Kp = 1.4


With x1 we get a partial pressure of:


Since negative partial pressure don´t make physical sense x1 is not the solution for the system.
With x2 we get:


These partial pressures make sense so x2 is the solution for the equation.
We follow the same analysis for the other values of Kp.
Kp=2*10^-4
X1=0.505
X2=0.495
With x1


Not sense.
With x2


X2 is the solution for this equation.
Kp=2*10^5
X1=50001

With x1


Not sense.
With x2


X2 is the solution for this equation.
Answer:
When the two atoms move towards each other a compound is formed by sharing electron pairs supplied by each of the atoms to enable them have the stable 8 (octet) valency electrons in their outermost shell
Explanation:
The electronic configuration of the given element can be written as follows;
1s²2s²2p⁴
The given electronic configuration is equivalent to that of oxygen, therefore, we have;
The number of electrons in the valence shell = 2 + 4 = 6 electrons
Therefore, each atom requires 2 electrons to complete its 8 (octet) electrons in the outermost shell
When the two atoms move towards each other, they react and combine to form a compound by sharing 4 electrons, 2 from each atom, such that each atom can have an extra 2 electrons in its outermost orbit in the newly formed compound and the stable octet configuration is attained by each of the atoms in the newly formed compound.