Question

arrange the following steps in the correct order to describe how students could demonstrate that mass is conserved in this reaction. a) measure the mass of the empty beaker. b) add the two liquids to the beaker and observe the reaction. c) measure the mass of the beaker with the reacting mixture. d) calculate the total mass of the original liquids. e) compare the final mass to the sum of the initial masses.

in a laboratory experiment, a student combined 5.0 grams of iron filings with 2.8 grams of sulfur powder in a test tube. after heating the mixture, a chemical reaction occurred, forming iron (ii) sulfide. the student recorded the mass of the product as 7.8 grams. using this data, explain how this experiment demonstrates the conservation of mass in chemical reactions. include any assumptions you need to make in your explanation.

Explanation:

For the first part (arranging steps to demonstrate mass conservation):

Step1: Measure empty beaker (A)

First, we need the mass of the empty beaker to later calculate the mass of the liquids.

Step2: Add liquids and observe (B)

Conduct the reaction by adding the two liquids to the beaker.

Step3: Measure beaker with mixture (C)

Get the mass of the beaker containing the reacting mixture after the reaction.

Step4: Calculate original liquids mass (D)

Subtract the mass of the empty beaker (from Step 1) from the mass of the beaker with liquids before reaction (though not measured directly here, conceptually we can calculate the mass of the liquids by knowing the beaker's mass and the beaker + liquids mass, but in the given steps, we assume we can calculate the total mass of original liquids, perhaps from their individual masses or other means).

Step5: Compare final and initial masses (E)

Compare the final mass (from Step 3) to the sum of the initial masses (from Step 4) to check conservation.

The law of conservation of mass states that in a closed system, the total mass of reactants equals the total mass of products in a chemical reaction. In this experiment, the reactants are iron filings (mass = 5.0 g) and sulfur powder (mass = 2.8 g). We assume that the reaction occurs in a closed system (so no mass is lost to the surroundings, like no gas escapes, and all reactants are converted to products). The total mass of reactants is calculated as the sum of the mass of iron and the mass of sulfur. So, total mass of reactants $m_{reactants}=5.0\ g + 2.8\ g=7.8\ g$. The mass of the product (iron (II) sulfide) is recorded as 7.8 g. Since the mass of the products (7.8 g) is equal to the mass of the reactants (7.8 g), this experiment demonstrates the conservation of mass in a chemical reaction.

Answer:

The correct order is A, B, C, D, E.

For the second part (explaining mass conservation in the iron - sulfur experiment):