Explain the law that the scientists used to predict that the product of the reaction would be 15.8 grams of copper sulfide
To explain the law that scientists used to predict the product of the reaction, we need to consider the concept of stoichiometry.
In chemistry, stoichiometry is the relationship between the quantities of reactants and products in a chemical reaction. It allows scientists to predict the amount of products formed based on the given amounts of reactants and the balanced chemical equation.
In this case, the scientists used stoichiometry to predict that the product of the reaction would be 15.8 grams of copper sulfide.
They would have started with a balanced chemical equation for the reaction. For example, let's consider the reaction between copper (Cu) and sulfur (S) to form copper sulfide (CuS):
Cu + S -> CuS
The balanced equation tells us that 1 mole of copper reacts with 1 mole of sulfur to produce 1 mole of copper sulfide.
Next, the scientists would have determined the molar ratio between copper and copper sulfide. By comparing the coefficients in the balanced equation, they would find that the ratio is 1:1. This means that for every 1 mole of copper, 1 mole of copper sulfide is produced.
Then, they would have converted the given amount of reactant (copper) to moles. Let's say the given amount is 15.8 grams of copper. By using the molar mass of copper (63.546 g/mol), they would have converted grams to moles.
Finally, using the mole-to-mole ratio from the balanced equation, they would determine the moles of copper sulfide formed. Since the ratio is 1:1, the moles of copper sulfide would also be 15.8.
To find the mass of copper sulfide, they would multiply the moles obtained by the molar mass of copper sulfide (which can be determined from its chemical formula). The result would be 15.8 grams of copper sulfide, as predicted by using the law of stoichiometry.
The law that the scientists used to predict the product of the reaction is the law of conservation of mass. According to this law, the total mass of the reactants before a chemical reaction is always equal to the total mass of the products after the reaction. In other words, atoms are not created or destroyed during a chemical reaction, they are rearranged.
In the specific reaction you mentioned, if the scientists predicted that the product would be 15.8 grams of copper sulfide, it means that they balanced the chemical equation for the reaction and determined the stoichiometry of the reaction. The balanced equation allows them to establish the ratio between the reactants and the products.
For example, if the balanced equation of the reaction is:
2Cu + S → Cu2S
This equation indicates that two moles of copper (Cu) combine with one mole of sulfur (S) to form one mole of copper sulfide (Cu2S). Using the molar masses of copper (63.55 g/mol), sulfur (32.07 g/mol), and copper sulfide (159.16 g/mol), we can calculate the predicted mass of copper sulfide:
Moles of Cu2S = Moles of Cu = (15.8 g Cu) / (63.55 g/mol Cu) = 0.2487 mol Cu
Moles of Cu2S = Moles of S = 0.2487 mol S
Therefore, the mass of 0.2487 moles of Cu2S is:
Mass of Cu2S = (0.2487 mol Cu2S) x (159.16 g/mol Cu2S) = 39.5 g Cu2S
Thus, based on the balanced equation and the law of conservation of mass, the scientists predicted that the product of the reaction would be 15.8 grams of copper sulfide.
To predict the product of a chemical reaction, scientists often rely on the law of conservation of mass. The law of conservation of mass states that in a closed system, the total mass of the reactants before a chemical reaction is equal to the total mass of the products after the reaction.
In this case, the scientists used the law of conservation of mass to determine the mass of copper sulfide that would be produced. They may have started with a known mass of reactants, such as copper and sulfur, and calculated the expected mass of the product, copper sulfide.
To calculate the expected mass of copper sulfide, the scientists likely used the concept of stoichiometry. Stoichiometry is based on the idea that chemical reactions occur in specific ratios of reactants and products. These ratios can be determined from the balanced chemical equation that represents the reaction.
For example, if the balanced chemical equation for the reaction is:
2Cu + S → Cu2S,
From this equation, we see that 2 moles of copper (Cu) react with 1 mole of sulfur (S) to produce 1 mole of copper sulfide (Cu2S).
To calculate the mass of copper sulfide, the scientists would need to know the molar mass of copper sulfide (Cu2S). By summing the atomic masses of the atoms in the formula Cu2S, they would determine the molar mass.
Once the molar mass is known, it can be used to convert moles of copper sulfide into grams using the relationship: g = moles × molar mass.
By applying stoichiometry and utilizing the law of conservation of mass, scientists can make predictions about the expected mass of products in a chemical reaction.