Log in to make full use of the services
Which sample of matter is classified as a substance?*
Which sample of matter represents a mixture?*
Which sample can be classified as a substance?*
All matter can be classified as*
Given the diagram representing a classification of matter:
Which types of matter are represented by X and Z in the diagram?*
A substance is classified as either an element or a*
Compared to a 26-gram sample of NaCl(s) at STP, a 52-gram sample of NaCl(s) at STP has*
Given four particle models:
Which two models can be classified as elements?*
Compared to a 15-gram sample of Cu(s) at 25°C, a 25-gram sample of Cu(s) at 25°C has*
At STP, which physical property of aluminum always remains the same from sample to sample?*
Base your answers to questions 11 on the information below.
Nitrogen gas and oxygen gas make up about 99% of Earth’s atmosphere. Other atmospheric gases include argon, carbon dioxide, methane, ozone, hydrogen, etc.
The amount of carbon dioxide in the atmosphere can vary. Data for the concentration of CO2(g) from 1960 to 2000 are shown in the table below.
Explain why the atmosphere is classified as a mixture.*
Base your answers to questions 12 on the information below and on your knowledge of chemistry.
In the late 19th century, the Hall-Herroult process was invented as an inexpensive way to produce aluminum. In this process, Al2O3(ℓ) extracted from bauxite is dissolved in Na3AlF6(ℓ) in a graphite-lined tank, as shown in the diagram below. The products are carbon dioxide and molten aluminum metal.
Compare the chemical properties of a 300.-kilogram sample of Al2O3(ℓ) with the chemical properties of a 600.-kilogram sample of Al2O3(ℓ).*
Base your answers to questions 13 on the information below.
Iron has been used for thousands of years. In the air, iron corrodes. One reaction for the corrosion of iron is represented by the balanced equation below.
Equation 1: 4Fe(s) + 3O2(g) → 2Fe2O3(s)
In the presence of water, iron corrodes more quickly. This corrosion is represented by the unbalanced equation below.
Equation 2: Fe(s) + O2(g) + H2O(ℓ) → Fe(OH)2(s)
Identify one substance in the passage that can not be broken down by a chemical change.*
Base your answers to questions 14 on the information below.
A scientist makes a solution that contains 44.0 grams of hydrogen chloride gas, HCl(g), in 200. grams of water, H2O(ℓ), at 20.°C. This process is represented by the balanced equation below.
Explain, in terms of the distribution of particles, why the solution is a homogeneous mixture.*
Base your answers to questions 15 on the information below and on your knowledge of chemistry.
A student prepares two 141-gram mixtures, A and B. Each mixture consists of NH4Cl, sand, and H2O at 15°C. Both mixtures are thoroughly stirred and allowed to stand. The mass of each component used to make the mixtures is listed in the data table below.
State evidence from the table indicating that the proportion of the components in a mixture can vary.*