Chemistry, 03.08.2019 22:30 wolfsaway

Correctly order the steps necessary to calculate the mass of product formed in a chemical reaction given the masses of all reactants

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1) write down balanced chemical reaction.
2) calculate the number of moles of a reagents.
3) determining molar ratios - identify the number of moles of each reactant needed to form a certain number of moles of each product.
4) from number of moles of each product calculate mass of products using molar mass.

Answer from: devinmoore8686

Answer : The order of steps necessary to calculate the mass of product formed in a chemical reaction given the masses of all reactants :

(1) Determine the number of moles of each reactant by dividing its mass by its molar mass.

(2) Identify the limiting reactant as the reactant that produces the least amount of product.

(3) Determine the amount of product that could be formed from the limiting reactant using appropriate mole ratio.

(4) Determine the mass, multiply the number of moles of product formed (from the limiting reactant) by the molar mass of the product.

For example :

If we are given that 10 grams of magnesium react with 6 grams of oxygen to give magnesium oxide then calculate the mass of product formed in a chemical reaction.

Solution :

Mass of Mg = 10 g

Mass of O_2 = 6 g

Molar mass of Mg = 24 g/mole

Molar mass of O_2 = 32 g/mole

Molar mass of MgO = 40 g/mole

First we have to calculate the moles of Mg and O_2 .

$\text{ Moles of }Mg=\frac{\text{ Mass of }Mg}{\text{ Molar mass of }Mg}=\frac{10g}{24g/mole}=0.4167moles$

$\text{ Moles of }O_2=\frac{\text{ Mass of }O_2}{\text{ Molar mass of }O_2}=\frac{6g}{32g/mole}=0.1875moles$

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

$2Mg(s)+O_2(g)\rightarrow 2MgO(s)$

From the balanced reaction we conclude that

As, 1 mole of O_2 react with 2 mole of

So, 0.1875 moles of O_2 react with $0.1875\times 2=0.375$ moles of

From this we conclude that, is an excess reagent because the given moles are greater than the required moles and O_2 is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of MgO

From the reaction, we conclude that

As, 1 mole of O_2 react to give 2 mole of MgO

So, 0.1875 moles of O_2 react to give $0.1875\times 2=0.375$ moles of MgO

Now we have to calculate the mass of MgO

$\text{ Mass of }MgO=\text{ Moles of }MgO\times \text{ Molar mass of }MgO$

$\text{ Mass of }MgO=(0.375moles)\times (40g/mole)=15g$

Hence, the mass of product is 15 grams.

Answer from: Quest

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.

chemical decomposition is opposite of chemical synthesis.

Answer from: Quest

frequency, z, and the collision density, z, in carbon dioxide (co2), r 180 pm at 30 °c and 120 kpa

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