Are you ready to take this lesson's quiz? These questions will help you find out. Make sure you understand why each correct answer is correct—if you don't, review that part of the lesson.
Which is a chemical property of iron?
- Iron corrodes in moist air.
- Iron's density is 7.874 g/cm3.
- Iron is soft when pure.
- Iron melts at 1,535 ℃.
Corrosion changes the chemical composition of iron.
Density can be measured without changing the make-up of the substance.
Hardness can be observed without changing the chemical make-up of the substance.
Melting point can be measured without changing the chemical make-up of the substance.
Which is a physical change?
- Decomposition of hydrogen peroxide into water and oxygen gas.
- Making a model volcano by mixing vinegar and baking soda.
- Activating an instant cold pack in a first aid kit.
- Using a chisel to carve a marble statue.
No new substances are created during a physical change.
Bubbling/foaming is a sign of the production of a gas, which is a sign of a chemical change.
A temperature change is a sign of a chemical change.
Physical changes alter the appearance of a substance without changing its composition.
Which is a sign of a chemical change?
- changing state of matter
- producing a precipitate
- destroying matter
- maintaining the same chemical composition
A phase change is a type of physical change.
A precipitate is a solid formed from a chemical reaction.
The law of conservation of mass states that matter is neither created nor destroyed, even during a chemical change.
A chemical change causes a change in the composition of the substance.
Which answer correctly identifies the reactants and products of the reaction being represented by this chemical equation?
\( HCl + NaOH \rightarrow NaCl + H_{2}O \)
- HCl and H2O are the reactants; NaOH and NaCl are the products
- NaOH and NaCl are the reactants; HCl and H2O are the products
- HCl and NaOH are the reactants; NaCl and H2O are the products
- NaCl and H2O are the reactants; HCl and NaOH are the products
The reactants are on the left side of the arrow and the products are on the right side of the arrow.
The reactants are on the left side of the arrow and the products are on the right side of the arrow.
The reactants are on the left side of the arrow and the products are on the right side of the arrow.
The reactants are on the left side of the arrow and the products are on the right side of the arrow.
When heated, a 50.0 gram sample of baking soda decomposes into sodium carbonate (Na2CO3), water, and carbon dioxide according to the equation below.
\( 2NaHCO_{3} \rightarrow \text{Na}_{2}CO_{3} + H_{2}O + CO_{2} \)
If 31.5 g of sodium carbonate and 5.4 g of water were produced, how much carbon dioxide was also produced?
- 36.9 g CO2
- 13.1 g CO2
- 50.0 g CO2
- 18.5 g CO2
According to the law of conservation of mass, the reactants and products must have the same mass. Therefore, \( 50.0 = 31.5 + 5.4 + x \), where \( x \) is the mass of the CO2. This answer just added \( 31.5 + 5.4 \).
According to the law of conservation of mass, the reactants and products must have the same mass. Therefore, \( 50.0 = 31.5 + 5.4 + x \), where \( x \) is the mass of the CO2.
According to the law of conservation of mass, the reactants and products must have the same mass. Therefore, \( 50.0 = 31.5 + 5.4 + x \), where \( x \) is the mass of the CO2. This answer is the mass of all products combined, not just the CO2 by itself.
According to the law of conservation of mass, the reactants and products must have the same mass. Therefore, \( 50.0 = 31.5 + 5.4 + x \), where \( x \) is the mass of the CO2. This answer only accounted for the sodium carbonate and carbon dioxide while neglecting the mass of water.
Summary
Questions answered correctly:
Questions answered incorrectly:
