Convert 250.0F into C

Why is the sun up sometimes but not other times?

MatroZZZ [7]

Answer: The Sun appears to move across the sky because the Earth rotates on its axis. ... When where you are is pointed toward the Sun, it is day. Then the Earth rotates you away from the Sun, and it is night.

Explanation:

6 0

3 years ago

Which of the following possess the greatest concentration of hydroxide ions?

jek_recluse [69]

Answer : The correct option is (d) a solution of 0.10 M NaOH

Explanation :

<u>(a) a solution of pH 3.0</u>

First we have to calculate the pOH.

$pH+pOH=14\\\\pOH=14-pH\\\\pOH=14-3.0=11$

Now we have to calculate the $OH^-$ concentration.

$pOH=-\log [OH^-]$

$11=-\log [OH^-]$

$[OH^-]=1.0\times 10^{-11}M$

Thus, the $OH^-$ concentration is, $1.0\times 10^{-11}M$

<u>(b) a solution of 0.10 M $NH_3$ </u>

As we know that 1 mole of $NH_3$ is a weak base. So, in a solution it will not dissociates completely.

So, the $OH^-$ concentration will be less than 0.10 M

<u>(c) a solution with a pOH of 12.</u>

We have to calculate the $OH^-$ concentration.

$pOH=-\log [OH^-]$

$12=-\log [OH^-]$

$[OH^-]=1.0\times 10^{-12}M$

Thus, the $OH^-$ concentration is, $1.0\times 10^{-12}M$

<u>(d) a solution of 0.10 M NaOH</u>

As we know that $NaOH$ is a strong base. So, it dissociates to give $Na^+$ ion and $OH^-$ ion.

So, 0.10 M of $NaOH$ in a solution dissociates to give 0.10 M of $Na^+$ ion and 0.10 M of $OH^-$ ion.

Thus, the $OH^-$ concentration is, 0.10 M

<u>(e) a $1\times 10^{-4}M$ solution of $HNO_2$ </u>

As we know that 1 mole of $HNO_2$ in a solution dissociates to give 1 mole of $H^+$ ion and 1 mole of $NO_2^-$ ion.

So, $1\times 10^{-4}M$ of $HNO_2$ in a solution dissociates to give $1\times 10^{-4}M$ of $H^+$ ion and $1\times 10^{-4}M$ of $NO_2^-$ ion.

The concentration of $H^+$ ion is $1\times 10^{-4}M$

First we have to calculate the pH.

$pH=-\log [H^+]$

$pH=-\log (1.0\times 10^{-4})$

$pH=4$

Now we have to calculate the pOH.

$pH+pOH=14\\\\pOH=14-pH\\\\pOH=14-4=10$

Now we have to calculate the $OH^-$ concentration.

$pOH=-\log [OH^-]$

$10=-\log [OH^-]$

$[OH^-]=1.0\times 10^{-10}M$

Thus, the $OH^-$ concentration is, $1.0\times 10^{-10}M$

From this we conclude that, a solution of 0.10 M NaOH possess the greatest concentration of hydroxide ions.

Hence, the correct option is (d)

3 0

3 years ago

How many moles of nitrogen, N, are in 61.0 g of nitrous oxide, N2O?

Oksana_A [137]

Answer:

2.77 mol N

Explanation:

M(N2O) = 2*14 + 16 = 44 g/mol

61.0 g * 1 mol/44g = (61/44) mol N2O

N2O ---- 2N

1 mol 2 mol

(61/44) mol x mol

x = (61/44)*2/1 = 2.77 mol N

4 0

3 years ago

If fluorine gas (F₂) occupies a volume of 45.5 L at a pressure of 850

pshichka [43]

Taking into account about the ideal gas law, the mass of fluorine gas is 63.2244 grams.

<h3>What is ideal gas law</h3>

An ideal gas is a theoretical gas that is considered to be composed of randomly moving point particles that do not interact with each other. Gases in general are ideal when they are at high temperatures and low pressures.

The pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:

P×V = n×R×T

where:

P is the gas pressure.
V is the volume that occupies.
T is its temperature. The universal constant of ideal gases R has the same value for all gaseous substances.
R is the ideal gas constant.
n is the number of moles of the gas.

<h3>Definition of molar mass</h3>

The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.

<h3>Mass of fluorine gas</h3>

In this case, you know:

P= 850 mmHg= 1.11842 atm (being 1 mmHg= 0.00131579 atm)
V= 45.5 L
T =100 °C= 373 K (being 0°C= 273 K)
R= 0.082 $\frac{atm L}{mol K}$
n= ?

Replacing in the ideal gas law:

1.11842 atm ×45.5 L = n×0.082 $\frac{atm L}{mol K}$ × 373 K

Solving:

n= (1.11842 atm ×45.5 L)÷ (0.082 $\frac{atm L}{mol K}$ × 373 K)

<u><em>n= 1.6638 moles</em></u>

The molar mass of F₂ is 38 g/mole. Then you can apply the folowing rule of three: If by definition of molar mass 1 mole of the compound contains 38 grams, 1.6638 moles of the compound contains how much mass?

$mass= \frac{1.6638 molesx38 grams}{1 mole}$