If the mass of elements before a chemical reaction is 30 grams, after the chemical reaction, the mass will be __.
30 grams
28 grams
0 grams
32 grams
The mass of the elements before a chemical reaction will always be equal to the mass of the elements after the chemical reaction, according to the law of conservation of mass. Therefore, after the chemical reaction, the mass will still be 30 grams.
78 g of potassium (K) react with 71 g of chlorine (CI) to produce potassium chloride. According to the Law of Conservation of Mass. What is the mass of the product?
149 g
4g
156 g
2g
To find the mass of the product, we need to add the masses of the reactants, since according to the Law of Conservation of Mass, mass is conserved in a chemical reaction.
Mass of potassium (K) = 78 g
Mass of chlorine (CI) = 71 g
Total mass of reactants = 78 g + 71 g = 149 g
Therefore, the mass of the product, potassium chloride, is 149 g.
2 grams of potassium (K) reacts with 5 grams of Oxygen (O). According to the Law of Conservation of Mass, how many grams of potassium oxide (K2O) will be produced?
To determine the mass of potassium oxide (K2O) produced, we first need to calculate the molar mass of each element involved.
- The molar mass of potassium (K) is 39.10 g/mol.
- The molar mass of oxygen (O) is 16.00 g/mol.
Next, we need to determine the molar ratio between potassium (K) and potassium oxide (K2O) in the balanced chemical equation to determine the stoichiometry.
The balanced chemical equation for the reaction between potassium and oxygen is:
4K + O2 -> 2K2O
From the balanced equation, we can see that for every 4 moles of potassium (K), 2 moles of potassium oxide (K2O) are produced.
Now, let's calculate the number of moles of potassium (K) and oxygen (O) based on the given masses:
- Moles of potassium (K) = mass / molar mass = 2 g / 39.10 g/mol ≈ 0.051 mol
- Moles of oxygen (O) = mass / molar mass = 5 g / 16.00 g/mol ≈ 0.313 mol
We can see from the balanced equation that the stoichiometric ratio between potassium (K) and potassium oxide (K2O) is 4:2. Therefore, the moles of potassium oxide (K2O) produced will be half the moles of potassium (K).
So, moles of potassium oxide (K2O) = 0.051 mol / 2 ≈ 0.0255 mol
Finally, let's calculate the mass of potassium oxide (K2O) produced:
Mass of potassium oxide (K2O) = moles * molar mass = 0.0255 mol * (39.10 * 2) g/mol ≈ 2 g
Therefore, approximately 2 grams of potassium oxide (K2O) will be produced according to the Law of Conservation of Mass.
Which of the following equations demonstrates the Law of Conservation of Mass?
CH4+O2 - CO2+H2O
CH+O2 - CO2+H2O
CH4+O2 - CO2+H2O
CH4+O2 - C+ 2H2O
The equation that demonstrates the Law of Conservation of Mass is:
CH4 + O2 -> CO2 + 2H2O
According to the Law of Conservation of Mass, the total mass of the reactants should be equal to the total mass of the products. In this equation, there are 1 carbon (C), 4 hydrogen (H), and 2 oxygen (O) atoms on both sides of the equation, ensuring mass is conserved.