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3 years ago

Determine the pH of 1.0 x 10-10M NaOH pH=

Chemistry

1 answer:

Mrrafil [7]3 years ago

7 0

Answer:

Explanation:

Applying,

pH = 14-pOH.................... Equation 1

But,

pOH = -log(OH⁻)

Where OH⁻ = Hydroxyl ion concentration of NaOH.

From the question,

Given: OH⁻ = (1×10⁻¹⁰) M

Substitute these values into equation 1

pH = 14-log((1×10⁻¹⁰)

pH = 14-10

pH = 4

Hence the pH of NaOH with a molarity of 1.0 x 10-10M = 4

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What geometry does VSEPR predict for the central atom in PF5

ddd [48]

so you can see those fluorine atoms have really spread out around the central phosphorus atom. this gives us a trigonal bi-pyramidal molecular geometry for pf5.

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3 years ago

Carbon-14 is a radioactive isotope that decays according to first-order kinetics in a process that has a half-life of 5730 years

Sliva [168]

Answer : The time passed in years is $2.83\times 10^3\text{ years}$

Explanation :

Half-life = 5730 years

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{5730\text{ years}}$

$k=1.21\times 10^{-4}\text{ years}^{-1}$

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $1.21\times 10^{-4}\text{ years}^{-1}$

t = time passed by the sample = ?

a = let initial amount of the reactant = X g

a - x = amount left after decay process = $71\% \times (x)=\frac{71}{100}\times (X)=0.71Xg$

Now put all the given values in above equation, we get

$t=\frac{2.303}{1.21\times 10^{-4}}\log\frac{X}{0.71X}$

$t=2831.00\text{ years}=2.83\times 10^3\text{ years}$

Therefore, the time passed in years is $2.83\times 10^3\text{ years}$

8 0

3 years ago

Identify the group of elements that corresponds to each of the following generalized electron configurations and indicate the nu

Alja [10]

Answer:

(a) [Noble gas] ns² np⁵: Number of unpaired electron is 1 and belongs to group 17 i.e. halogen group of the periodic table.

(b) [noble gas] ns² (n-1)d²: Number of unpaired electron is 2 and belongs to group 4 of the periodic table.

(c) [noble gas] ns² (n-1)d¹⁰ np¹: Number of unpaired electron is 1 and belongs to group 13 of the periodic table.

(d)[noble gas] ns² (n-2)f⁶ : Number of unpaired electron is 6 and belongs to group 8 of the periodic table.

Explanation:

In the Periodic table, the chemical elements are arranged in 7 rows, called periods and 18 columns, called groups. They are organized in increasing order of atomic numbers.

(a) [Noble gas] ns² np⁵

As the total number of electrons in the p-orbital is 5. Therefore, the number of unpaired electron is 1.

This element has 2 electrons in ns orbital and 5 electrons in np orbital. So there are 7 valence electrons.

Therefore, this element belongs to the group 17 i.e. halogen group of the periodic table.

(b) [noble gas] ns² (n-1)d²

As the total number of electrons in the d-orbital is 2. Therefore, the number of unpaired electrons is 2.

This element has 2 electrons in ns orbital and 2 electrons in (n-1)d orbital. So there are 4 valence electrons.

Therefore, this element belongs to the group 4 of the periodic table.

(c) [noble gas] ns² (n-1)d¹⁰ np¹

As the total number of electrons in the p-orbital is 1. Therefore, the number of unpaired electron is 1.

This element has 2 electrons in ns orbital and 1 electron in np orbital. So there are 3 valence electrons.

Therefore, this element belongs to the group 13 of the periodic table.

(d)[noble gas] ns² (n-2)f⁶

As the total number of electrons in the f-orbital is 6. Therefore, the number of unpaired electron is 6.

This element has 2 electrons in ns orbital and 6 electrons in (n-2)f orbital. So there are 8 valence electrons.

Therefore, this element belongs to the group 8 of the periodic table.

3 0

3 years ago

Cathode rays were shown to be a stream of _____. protons electrons neutrons quarks

Murljashka [212]

It's B) electrons, is the right answer

7 0

3 years ago

An isotope of carbon has 8 neutrons. What is the correct hyphenated symbol for this isotope?

Rom4ik [11]

Answer:

Carbon-14 or C-14

Explanation:

Since the isotope is a carbon isotope, it means the the atomic number of the isotope is 6.

The atomic number of an element is the proton number.

Therefore, the isotope has a proton number of 6

Now we need to obtain the mass number of isotope in order to write the symbol of the isotope. This is illustrated below:

Mass number = Proton +Neutron

Proton = 6

Neutron = 8

Mass number = 6 + 8

Mass number = 14

Therefore, the symbol of the isotope is carbon-14 or C-14

4 0

4 years ago