Interpret Substance Interaction Data Practice Test

A strip of magnesium metal reacts with hydrochloric acid in a sealed container (so no gas can escape). The container is placed on a balance.

Before reaction:

• Container + 50.0 g HCl(aq) + 0.50 g Mg(s): total mass = 150.50 g, temperature = 22.0°C

After reaction stops:

• Container + products: total mass = 150.50 g, temperature = 30.0°C, visible bubbles formed during reaction

What does the data indicate?

A student combines two substances in a sealed container and records mass and temperature.

Before:

• Substance A (solid): mass = 6.0 g, temperature = 19.0°C, color = white
• Substance B (liquid): mass = 14.0 g, temperature = 19.0°C, color = clear
• Total mass (sealed container + contents): 120.0 g

After shaking (still sealed):

• Contents: temperature = 30.0°C, color = yellow, no visible pieces of solid A remain
• Total mass (sealed container + contents): 120.0 g

Which conclusion is best supported by the data?