Topic-+Substances,+Chemical+Reactions,+and+Conservation+of+Matter

Topic: Substances, Chemical Reactions, and Conservation of Matter
Below is a list of key ideas related to Substances, Chemical Reactions, and Conservation of Matter. For each key idea, you will find a list of sub-ideas, a list of items, results from our field testing, and a list of student misconceptions. After clicking on a tab, click on it again to close the tab.

A pure substance has characteristic properties, such as density, a boiling point, and solubility, all of which are independent of the amount of the substance and can be used to identify it.
//Students are expected to know that:// //Boundaries://
 * [|Sub-Ideas]
 * [|Items & Student Performance]
 * [|Misconceptions]
 * 1) Note: The term “characteristic property” is used to emphasize that these properties are defining attributes that are independent of the amount of the sample, regardless of time, location, size, or shape.
 * 2) The term “substance” means a pure material that is made of the same matter throughout. This is in contrast to the common definition that equates substance with matter that could be made of either a single substance or a mixture of more than one substance. To make this explicit, the phrase “pure substance” is used in assessment items.
 * 3) A substance can be a solid, a liquid, or a gas.
 * 4) Every substance has a set of characteristic properties that are always the same for that substance, regardless of time, location, shape, or size.
 * 5) Furthermore, characteristic properties are consistent throughout a sample of a substance.
 * 6) Characteristic properties with which students should be familiar are boiling point, melting and freezing point, solubility (i.e. how much of the substance can dissolve in water), flammability (i.e. the ease with which a substance will catch on fire), odor, color, and density (i.e., that equal volumes of different substances have different masses).
 * 7) Weight, mass, volume, shape, length/width, texture, and temperature are not characteristic properties of substances and may change.
 * 8) The characteristic properties of a substance do not change when temperature and pressure remain the same.
 * 9) No two substances can have the same set of characteristic properties under the same conditions and that if two materials have even one different characteristic property, they are different substances.
 * 1) Students are not expected to know that the properties of substance can be different at the nanoscale.
 * 2) They are not expected to know the formula for density (density = mass/volume).
 * 3) Students are not expected to know that the atomic mass of a substance is a characteristic property.
 * 4) They are not expected to know whether specific materials are or are not pure substances.
 * 5) Because some properties do change with changing conditions (e.g., changing atmospheric pressure affects boiling point) all assessment items will make comparisons between substances where it is clear that the conditions, such as temperature and pressure, are constant.

Percent of students answering correctly (click on the item ID number to view the item and additional data)||~ Item ID Number ||~ Knowledge Being Assessed 6–8 ||~ Grades 9–12 ||~ Select This Item for My Item Bank ||
 * ~ Grades
 * [|SC095003] || [|To help identify a metal, you could determine its density and compare it to the density of other metals.] || 56% || 61% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1536"]] ||
 * [|SC095002] || [|To help identify a metal, you could determine its melting point and compare it to the melting point of other metals.] || 55% || 59% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1535"]] ||
 * [|SC064007] || [|Two liquids with the same density and color but different boiling points are different substances. (This item uses a table that lists properties of the liquids.)] || 53% || 54% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1869"]] ||
 * [|SC063004] || [|To identify a liquid, you could determine the boiling point of the liquid and compare it to the boiling points of other liquids.] || 50% || 58% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1532"]] ||
 * [|SC057008] || [|Two solids with the same melting point and color could be the same substance. (This item uses a table that lists properties of the solids.)] || 46% || 57% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1868"]] ||
 * [|SC044004] || [|If a piece of wax is removed from a ball of wax, the mass of the ball of wax would change but its melting point would stay the same.] || 46% || 59% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1912"]] ||
 * [|SC057007] || [|Two solids with the same melting point and color could be the same substance. (This item uses a table that lists properties of the solids.)] || 46% || 56% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1867"]] ||
 * [|SC046005] || [|How much of a substance dissolves in water is a characteristic property of the substance.] || 35% || 52% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1866"]] ||
 * [|SC100003] || [|Two liquids with the same flammability, boiling point, and color could be the same substance. (This item uses a table that lists properties of the solids.)] || 37% || 47% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1876"]] ||
 * [|SC064008] || [|Two liquids with the same density and color but different boiling points are different substances. (This item uses a table that lists properties of the liquids.)] || 41% || 43% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1870"]] ||
 * [|SC100004] || [|Two liquids with the same boiling point and color could be the same substance. (This item uses a table that lists properties of the liquids.)] || 31% || 44% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1877"]] ||
 * [|SC099002] || [|Determining the mass of a liquid and comparing its mass to the mass of other liquids will NOT help you identify the liquid.] || 30% || 36% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1538"]] ||
 * [|SC061004] || [|Smelling two liquids can help a student determine if the liquids are the same substance.] || 29% || 34% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1531"]] ||
 * [|SC096003] || [|To decide if two gases are the same substance, you could compare the odor of the two gases.] || 23% || 24% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1874"]] ||

Frequency of selecting a misconception||~ Misconception ID Number 6–8 ||~ Grades 9–12 || Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.
 * ~ Student Misconception ||~ Grades
 * [|SCM053] || [|If two substances share one characteristic property, they are the same substance (AAAS Project 2061, n.d.).] || 35% || 34% ||
 * [|SCM069] || [|The melting point of a substance is dependent on the amount of substance. For example, the melting point of a ball of wax will change if a piece of wax is removed from the ball (AAAS Project 2061, n.d.).] || 39% || 27% ||
 * [|SCM079] || [|Melting point is not a characteristic property of a pure substance.] || 32% || 27% ||
 * [|SCM058] || [|Volume is a characteristic property of a substance (DeBoer et al., 2009).] || 31% || 26% ||
 * [|SCM076] || [|Color is not a characteristic property of a pure substance.] || 29% || 24% ||
 * [|SCM078] || [|Boiling point is not a characteristic property of a pure substance.] || 21% || 22% ||
 * [|SCM081] || [|Density is not a characteristic property of a pure substance.] || 21% || 21% ||
 * [|SCM054] || [|If most of the listed characteristic properties are the same, the substances are the same (AAAS Project 2061, n.d.).] || 20% || 22% ||
 * [|SCM057] || [|Mass/weight is a characteristic property of a substance (DeBoer et al., 2009).] || 21% || 20% ||
 * [|SCM023] || [|Temperature is a characteristic property of the substance (Thomaz et al., 1995).] || 20% || 18% ||
 * [|SCM080] || [|Freezing point is not a characteristic property of a pure substance.] || 20% || 16% ||
 * [|SCM077] || [|Flammability is not a characteristic property of a pure substance.] || 15% || 15% ||
 * [|SCM061] || [|Shape is a characteristic property of a substance (AAAS Project 2061, n.d.).] || 12% || 10% ||
 * [|SCM060] || [|Length is a characteristic property of a substance (AAAS Project 2061, n.d.).] || 10% || 11% ||
 * [|SCM059] || [|Width is a characteristic property of a substance (AAAS Project 2061, n.d.).] || 11% || 7% ||

Many substances react chemically in predictable ways with other substances to form new substances with different characteristic properties.
//Students are expected to know that:// //Boundaries://
 * [|Sub-Ideas]
 * [|Items & Student Performance]
 * [|Misconceptions]
 * 1) When substances react chemically one or more new substances are formed.
 * 2) If a new substance does not appear, a chemical reaction did not occur.
 * 3) The products of a chemical reaction can be identified as new substances because each product has different characteristic properties from the original substances under the same conditions.
 * 4) Liquids, solids, or gases can be reactants or products in chemical reactions.
 * 5) It is possible for a single substance to undergo a chemical reaction, such as when the substance is heated or an electrical current flows through the substance.
 * 6) It is not true that all chemical reactions are irreversible.
 * 1) Students are not expected to know that chemical reactions involve the rearrangement of atoms into new molecules. This idea is addressed in a later idea (Idea D).
 * 2) Students are also not expected to know that nuclear reactions are not chemical reactions nor why nuclear reactions are not chemical reactions. Nuclear reactions are addressed in later ideas (4E/H6* and 4G/H6*)
 * 3) By “predictable ways,” we mean that the same products will be formed when the same reactants are combined regardless of location and experimental set-up. Students are not expected to predict what the products of a reaction will be.
 * 4) Students are expected to know that the original substances in a chemical reaction are called reactants and the resulting substances are called products but they will not be assessed on these definitions.

Percent of students answering correctly (click on the item ID number to view the item and additional data)||~ Item ID Number ||~ Knowledge Being Assessed 6–8 ||~ Grades 9–12 ||~ Select This Item for My Item Bank ||
 * ~ Grades
 * [|SC072004] || [|Chemical reactions produce solids, liquids, or gases.] || 67% || 69% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1882"]] ||
 * [|SC072003] || [|Chemical reactions produce solids, liquids, or gases.] || 63% || 67% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1881"]] ||
 * [|SC069007] || [|When a chemical reaction occurs, the characteristic properties of the products are different than the characteristic properties of the reactants. (This item used a table to show the properties of the substances.)] || 55% || 65% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1840"]] ||
 * [|SC049003] || [|A chemical reaction always results in the formation of a new substance, which can be a solid, liquid, or gas.] || 58% || 62% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1192"]] ||
 * [|SC029003] || [|Forming a white solid by mixing two clear liquids is an example of a chemical reaction.] || 51% || 59% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1560"]] ||
 * [|SC101003] || [|Bubbles of gas forming as a seashell is placed in vinegar is an example of a chemical reaction.] || 51% || 59% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1880"]] ||
 * [|SC071003] || [|The surface of a copper penny changing color after being in a drawer for years is an example of a chemical reaction.] || 40% || 52% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1879"]] ||
 * [|SC065004] || [|Burning a marshmallow is an example of a chemical reaction.] || 35% || 48% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1878"]] ||
 * [|SC067003] || [|When two liquids are mixed together and a solid forms, the solid is a new substance that was formed during a chemical reaction between the two liquids.] || 37% || 41% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1563"]] ||
 * [|SC073002] || [|Some chemical reactions can be reversed.] || 16% || 24% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1611"]] ||

Frequency of selecting a misconception||~ Misconception ID Number 6–8 ||~ Grades 9–12 || Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.
 * ~ Student Misconception ||~ Grades
 * [|SCM038] || [|Chemical reactions involve only two reactants (Cavallo et al., 2003; Eilks et al., 2007).] || 66% || 58% ||
 * [|SCM036] || [|A chemical change is irreversible (Cavallo et al., 2003; Calik et al., 2005).] || 36% || 34% ||
 * [|SCM020] || [|A chemical reaction occurs when a substance dissolves (Novak et al., 1991; BouJaoude, 1992; Abraham et al., 1994; Ahtee et al., 1998; Stavridou et al., 1998; Valanides, 2000; Eilks et al., 2007)] || 29% || 21% ||
 * [|SCM019] || [|A chemical reaction occurs during a change of state (Hall, 1973; Novak et al., 1991; BouJaoude, 1992; Ahtee et al., 1998; Stavridou et al., 1998).] || 19% || 16% ||
 * [|SCM070] || [|A chemical reaction always happens when two substances are combined together (AAAS Project 2061, n.d.).] || 18% || 16% ||
 * [|SCM040] || [|Chemical reactions involve only the production of gas (Cavallo et al., 2003).] || 11% || 13% ||
 * [|SCM039] || [|Chemical reactions involve liquids only (Cavallo et al., 2003).] || 13% || 11% ||
 * [|SCM056] || [|A chemical reaction always happens when two liquids are combined together (DeBoer et al., 2008).] || 15% || 9% ||
 * [|SCM063] || [|Chemical reactions occur between solids and liquids but not between solids and gases (AAAS Project 2061, n.d.).] || 12% || 10% ||
 * [|SCM037] || [|All chemical reactions are inherently dangerous (Cavallo et al., 2003).] || 11% || 11% ||
 * [|SCM062] || [|A solid substance is always formed during a chemical reaction (DeBoer et al., 2008).] || 9% || 8% ||
 * [|SCM002] || [|A chemical reaction must take place in a laboratory (Herrmann-Abell et al., 2009).] || 8% || 7% ||

When substances interact to form new substances, the atoms that make up the molecules of the original substances rearrange into new molecules.
//Students are expected to know that:// //Boundaries://
 * [|Sub-Ideas]
 * [|Items & Student Performance]
 * [|Misconceptions]
 * 1) During a chemical reaction the atoms that are linked together in molecules (or arranged in other patterns such as arrays and crystals) rearrange to make new molecules.
 * 2) If the atoms are not rearranged, then a chemical reaction has not occurred.
 * 3) New substances are made of the same kinds of atoms as the original substances (i.e., the atoms themselves did not change during the reaction).
 * 1) The idea that the number of each kind of atom stays the same will be assessed under Idea H (conservation of matter).
 * 2) Students are not expected to know the term “bond” or how chemical bonds are formed or broken during chemical reactions.
 * 3) They are not expected to know that during chemical reactions, atoms are not turned into energy.

Percent of students answering correctly (click on the item ID number to view the item and additional data)||~ Item ID Number ||~ Knowledge Being Assessed 6–8 ||~ Grades 9–12 ||~ Select This Item for My Item Bank ||
 * ~ Grades
 * [|SC066005] || [|When two white powders react to form a yellow powder, the yellow powder is made up of the same kinds of atoms as the white powders, but the atoms are combined into different molecules.] || 47% || 57% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1842"]] ||
 * [|SC060004] || [|Carbon atoms are not part of the products of the reaction between sulfur and oxygen. (This item uses circles to represent atoms.)] || 48% || 52% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1614"]] ||
 * [|SC093003] || [|During a chemical reaction, atoms stay the same but rearrange to form new molecules. (This item uses circles to represent atoms.)] || 39% || 50% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1887"]] ||
 * [|SC070004] || [|During a chemical reaction, atoms stay the same but rearrange to form new molecules. (This item uses circles to represent atoms.)] || 38% || 48% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1886"]] ||

Frequency of selecting a misconception||~ Misconception ID Number 6–8 ||~ Grades 9–12 || Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.
 * ~ Student Misconception ||~ Grades
 * [|SCM026] || [|The atoms of the reactants of a chemical reaction are transformed into other atoms (Andersson, 1986).] || 47% || 40% ||
 * [|SCM072] || [|The products of a chemical reaction are just a modified form of the reactants (Andersson, 1986).] || 25% || 19% ||
 * [|SCM016] || [|The products of a chemical reaction, though unseen, must have somehow existed from the start in another location, such as in the air or inside the reactants (Andersson, 1986; Solomonidou et al., 2000).] || 17% || 15% ||
 * [|SCM021] || [|After a chemical reaction, the product is a mixture in which the old substances persist, and is not a new substance (Johnson, 2000b).] || 17% || 13% ||
 * [|SCM025] || [|The reactants and products of a chemical reaction are different and independent of each other. There is no recognition of a change of one sample to the other (Johnson, 2000b).] || 11% || 9% ||

No matter how substances within a closed system interact with one another, the total mass of the system remains the same.
//Students are expected to know that:// //Boundaries://
 * [|Sub-Ideas]
 * [|Items & Student Performance]
 * [|Misconceptions]
 * 1) When substances mix, undergo chemical reactions, change state, or dissolve, or when objects are cut or broken into smaller pieces, the total mass of all the matter will always remain the same.
 * 2) Regardless of the form that the products of these processes may take (for example, when a sugar cube dissolves in water or a chemical reaction produces a gas), the mass will always stay the same.
 * 3) If it appears that the mass has changed, it is because some material has not been accounted for.
 * 4) Because light is not matter, its presence or absence does not affect the mass of the matter.
 * 1) Students are not expected to know that mass is not conserved in energy-mass conversions such as nuclear reactions or other subatomic interactions.
 * 2) Note: The words “weight,” “weigh,” and “mass” are used appropriately in the assessment items. The students are not expected to know the difference between “weight” and “mass.”

Percent of students answering correctly (click on the item ID number to view the item and additional data)||~ Item ID Number ||~ Knowledge Being Assessed 6–8 ||~ Grades 9–12 ||~ Select This Item for My Item Bank ||
 * ~ Grades
 * [|SC078003] || [|Mass is conserved when a stick of butter is cut into pieces.] || 70% || 73% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1633"]] ||
 * [|SC056004] || [|The weight of a jar containing water and sugar stays the same after some of the sugar dissolves.] || 37% || 53% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1628"]] ||
 * [|SC094004] || [|Mass is conserved when a plant dies in a sealed jar.] || 36% || 49% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1890"]] ||
 * [|SC059004] || [|When a chemical reaction occurs in a sealed container, the mass of the materials in the container stays the same.] || 31% || 48% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1629"]] ||
 * [|SC084004] || [|As a thermometer is heated and the level of liquid in the thermometer rises, the mass of the liquid stays the same.] || 29% || 44% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1889"]] ||
 * [|SC077005] || [|If a chemical reaction occurs between two liquids in a sealed jar, the mass will not change if a gas is formed, and it will not change if a solid is formed.] || 24% || 34% || [[image:http://assessment.aaas.org/img/star_16x16_grey.png link="http://assessment.aaas.org/users/itembank/add/1929"]] ||

Frequency of selecting a misconception||~ Misconception ID Number 6–8 ||~ Grades 9–12 || Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.
 * ~ Student Misconception ||~ Grades
 * [|SCM029] || [|Mass is not conserved during processes in which gases take part (Mas et al., 1987; Berkheimer et al., 1988; Hesse et al., 1992). If a gas is produced during a chemical reaction that takes place in a closed system, the total mass decreases (Ozmen et al., 2003).] || 55% || 50% ||
 * [|SCM032] || [|In a closed system, the total mass increases during a precipitation reaction (Barker et al., 1999; Ozmen et al., 2003).] || 54% || 49% ||
 * [|SCM064] || [|When a liquid in a closed container is heated, the mass of the liquid increases as the liquid expands (AAAS Project 2061, n.d.).] || 48% || 34% ||
 * [|SCM041] || [|During biological decomposition in a closed system, the total mass of the system decreases (Mitchell et al., 1984).] || 41% || 32% ||
 * [|SCM028] || [|In a closed system, mass decreases after a solid dissolves in a liquid (Stavy, 1990b; Ozmen et al., 2003).] || 27% || 20% ||
 * [|SCM027] || [|When a chemical reaction occurs, matter just disappears. For example, gasoline is used up in the car and disappears (Andersson, 1986).] || 16% || 11% ||
 * [|SCM051] || [|Mass increases after a solid dissolves in a liquid (Stavy, 1990b).] || 15% || 13% ||
 * [|SCM010] || [|Matter can disappear with repeated division, dissolving, evaporation, or chemical change (Smith et al., 2004).] || 10% || 10% ||

Whenever atoms interact with each other, regardless of how they are arranged or rearranged, the total mass stays the same.

 * [|Sub-Ideas]
 * [|Items & Student Performance]
 * [|Misconceptions]