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3 years ago

An atom with5 protons 6 neutrons and 5 electrons has an atomic mass of Amy

1 answer:

8 0

Answer: The number of neutrons for a given element is the only number that can change and still have the identity of the element stay the same, (because the atomic number is the number of protons). In this case the mass number would be 11.

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What is the molarity of a solution that contains 224 grams of KOH in 2<br> liters of solution?

adelina 88 [10]

Answer:

$\boxed {\boxed {\sf 2 \ M \ KOH}}$

Explanation:

Molarity is a measure of concentration in moles per liter.

<h3>1. Grams to Moles </h3>

The first step is to convert the amount of grams given to moles. The molar mass is used. This found on the Periodic Table and it's the same value as the atomic mass, but the units are grams per mole.

We have 224 grams of KOH. Look up the molar masses for the individual elements.

Potassium (K): 39.098 g/mol
Oxygen (O): 15.999 g/mol
Hydrogen (H): 1.008 g/mol

Since the compound's formula has no subscripts, 1 formula unit has 1 atom of each element. We can simply add the molar masses together to find KOH's molar mass.

KOH: 39.098 + 15.999 + 1.008=56.105 g/mol

Use this number as a ratio.

$\frac {56.105 \ g\ KOH}{1 \ mol \ KOH}$

Multiply by the value we are converting: 224 g KOH

$224 \ g \ KOH *\frac {56.105 \ g\ KOH}{1 \ mol \ KOH}$

Flip the ratio so the units of grams KOH cancel.

$224 \ g \ KOH *\frac {1 \ mol \ KOH}{56.105 \ g\ KOH}$

$224 *\frac {1 \ mol \ KOH}{56.105}$

$\frac {224}{56.105} \ mol \ KOH$

$3.992514036 \ mol \ KOH$

<h3>2. Calculate Molarity </h3>

Remember molarity is moles per liter.

$molarity = \frac{moles}{liters}$

We just calculated the moles and we know there are 2 liters of solution.

$molarity = \frac{ 3.992514036 \ mol \ KOH}{ 2 \ L}$

$molarity= 1.996257018 \ mol \ KOH/ L$

<h3>3. Round and Convert Units </h3>

First, let's round. The original values have 3 and 1 significant figures. We go with the lowest number: 1. For the number we found, that is the ones place.