Types of Reactions and Pure Sub vs. Mixtures Test

Carbonic acid (H₂CO₃) forms carbon dioxide (CO₂) and water (H₂O)during a decomposition reaction. Which of these represents the reactant side of the chemical reaction?

• H2CO3

• H2O + CO2

• CO2 + H2CO3

• H2O + CO2 + H2CO3

Answer explanation

In a decomposition reaction, there is only ONE reactant that is breaking down into two or more products. H2CO3 "forms" H2O and CO2, therefore H2CO3 is the reactant in this case.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-1

The chemical equation shows the reaction between hydrogen fluoride (HF) and sodium hydroxide (NaOH).
​
HF + NaOH → H₂​O+ NaF
​
Which type of chemical reaction does this equation represent?

• Decomposition

• Combustion

• Double Replacement

• Single Replacement

Answer explanation

The reaction is considered to be a double replacement, as there are two compounds within the reactant side of the equation. With there being two compounds, these compounds are going to swap "partners" in order to create two new products. With there being two "swaps" this is considered to be a double replacement reaction.

What type of reaction is represented by this balanced equation?

• Synthesis

• Decomposition

• Combustion

• Single Replacement

Answer explanation

In a synthesis reaction, two reactants bond together to form one product. In this example, Sulfur and Oxygen are bonding to form Sulfur Dioxide.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What are the products of this equation?

• 
• 
• 
• 

Answer explanation

When looking at the reactants, we can identify the reaction as a single replacement reaction. This is due to there being one element and one compound present in the reactants. The single element is going to replace one of the elements in the compound to form a new compound. In this case, Barium (Ba) is going to replace Copper (Cu) to form Barium Chloride (BaCl2), leaving Copper to be by itself.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What type of chemical reaction is represented by the balanced equation?

• Combustion

• Synthesis

• Single Replacement

• Decomposition

Answer explanation

In a combustion reaction, a hydrocarbon (CxHy- any number of carbon atoms bonded with any number of hydrogen atoms) reacts with Oxygen (O2) to form Carbon Dioxide (CO2) and Water (H2O).

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

​A student concludes that the unknown chemical acts as a catalyst. Which evidence from the graph supports the student’s conclusion?

• The amount of product increased when the chemical was added

• The chemical remained unchanged at the end of the reaction

• The rate of reaction increased when the chemical was added

• The chemical caused a reduction in the rate of reaction.

Answer explanation

The graph is demonstrating how adding a catalyst affects the rate of the reaction. When looking at the graph, the line that represents adding the unknown chemical has a higher reaction rate when compared to the line that represents without the unknown chemical. From this, we can deduce that by adding a catalyst, the rate of reaction will increase.

Tags

NGSS.MS-PS1-2

A student observed that the rate of a chemical reaction increased as the temperature of the system increased.
Which of the following statements best explains why thermal energy caused an increase in the reaction rate?

• The surface area of the product particles decreased

• The collision rate of the reactant particles increased

• The concentration of the reactant particles increased

• The concentration of the product particles decreased

Answer explanation

When adding thermal energy, this causes the speed of the particles to increase. By increasing the speed of the particles, you are also increasing the likelihood that these particles will collide with other reactants thereby increasing the speed of the reaction.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Which factor is causing Test Tube B to have a faster rate of reaction?

• Presence of a catalyst

• Greater surface area of Aluminum

• Greater concentration of Aluminum

• Higher temperature

Answer explanation

The higher the temperature, the faster the speed of the reaction. We observed this in our Alka-Seltzer lab when we compared the speed of reaction of cold water vs hot water. The hot water had a faster speed of reaction.

Tags

NGSS.MS-PS1-4

Which of the following are factors that affect the rate of reaction?

• Temperature

• Concentration

• State of Matter

• Presence of a catalyst

Answer explanation

The factors that influence the rate of reaction are: Temperature, Concentration, Surface Area, and Presence of a Catalyst.

Tags

NGSS.HS-PS1-5

In Investigation 2, an exothermic reaction occurred as energy was released. What is the best evidence that an exothermic reaction occurred in the beaker?

• The mass decreased

• The bubbling stopped

• There was a change in color

• There was an increase in temperature

Answer explanation

In an exothermic reaction, energy is released from the substance, causing the temperature to increase.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

NGSS.MS-PS3-4

NGSS.MS-PS3-5