Which representation of a chemical reaction is correct

Bases turns red litmus blue. Which base is found in window cleaner? Which method of separation is used for seperating heavier and lighter components by bowing air? Which among the following pairs is not correctly matched? Which among the following had not been discovered by the time when Mendeleev published his periodic table? Which among the following is called the 'Fool's Gold'? Which type of chemical reaction is responsible for turning the rocks red or yellowish?

Suggested Test Series. Suggested Exams. More General Science Questions Q1. What is Rodenticide? Prokaryotic Cell - One chromosome II. Eukaryotic Cells - More than one chromosome. In a convex lens, when the object is placed at infinity, where is the image formed? Testbook Edu Solutions Pvt. For example, a compound in the gas state would be indicated by g , solid s , liquid l , and aqueous aq.

Aqueous means dissolved in water; it is a common state of matter for acids, bases, and dissolved ionic compounds. It also indicates that two oxygen molecules are required for every methane molecule, and that the reaction will form two water molecules and one carbon dioxide molecule for every methane and two oxygen molecules that react.

The equation also identifies that all the compounds are in the gaseous state. Also, please note that, as in the mathematical commutative property of addition, chemical equations are commutative. Reactants and products can be written in any order, provided they are on the appropriate side of the reaction arrow. Symbols are used to differentiate among different types of reactions. Sometimes, different arrows are used to indicate something about the reaction.

For example:. If the reaction requires energy, it is often indicated above the arrow. When a baking soda volcano is made by mixing vinegar dilute aqueous acetic acid and baking soda sodium bicarbonate , the resulting evolution of gas occurs via the following reaction:. Matter cannot be created or destroyed, so there must be the same number of atoms of each element on each side of a chemical equation. A chemical equation is an expression of the net composition change associated with a chemical reaction.

It shows how a certain amount of reactants yields a certain amount of products. Both of these amounts are measured in moles.

Chemical equations often contain information about the state of the reactants: solid, liquid, gas, or aqueous. In addition, they always adhere to the law of conservation of mass, which holds that matter can change form, but cannot be created or destroyed. This means that the mass of a closed system of substances will remain constant, regardless of the processes acting inside the system.

This ratio is satisfied if the numbers of these molecules are, respectively, , or , or , and so on Figure 2. Likewise, these coefficients may be interpreted with regard to any amount number unit, and so this equation may be correctly read in many ways, including:. The chemical equation described in section 4.

This is a requirement the equation must satisfy to be consistent with the law of conservation of matter. It may be confirmed by simply summing the numbers of atoms on either side of the arrow and comparing these sums to ensure they are equal. If an element appears in more than one formula on a given side of the equation, the number of atoms represented in each must be computed and then added together.

For example, both product species in the example reaction, CO 2 and H 2 O, contain the element oxygen, and so the number of oxygen atoms on the product side of the equation is. The equation for the reaction between methane and oxygen to yield carbon dioxide and water is confirmed to be balanced per this approach, as shown here:.

A balanced chemical equation often may be derived from a qualitative description of some chemical reaction by a fairly simple approach known as balancing by inspection. Consider as an example the decomposition of water to yield molecular hydrogen and oxygen. This process is represented qualitatively by an unbalanced chemical equation:. Comparing the number of H and O atoms on either side of this equation confirms its imbalance:.

The numbers of H atoms on the reactant and product sides of the equation are equal, but the numbers of O atoms are not. To achieve balance, the coefficients of the equation may be changed as needed. Keep in mind, of course, that the formula subscripts define, in part, the identity of the substance, and so these cannot be changed without altering the qualitative meaning of the equation.

The O atom balance may be achieved by changing the coefficient for H 2 O to 2. The H atom balance was upset by this change, but it is easily reestablished by changing the coefficient for the H 2 product to 2. These coefficients yield equal numbers of both H and O atoms on the reactant and product sides, and the balanced equation is, therefore:. Balancing Chemical Equations Write a balanced equation for the reaction of molecular nitrogen N 2 and oxygen O 2 to form dinitrogen pentoxide. Next, count the number of each type of atom present in the unbalanced equation.

Though nitrogen is balanced, changes in coefficients are needed to balance the number of oxygen atoms. To balance the number of oxygen atoms, a reasonable first attempt would be to change the coefficients for the O 2 and N 2 O 5 to integers that will yield 10 O atoms the least common multiple for the O atom subscripts in these two formulas. The N atom balance has been upset by this change; it is restored by changing the coefficient for the reactant N 2 to 2.

The numbers of N and O atoms on either side of the equation are now equal, and so the equation is balanced. Check Your Learning Write a balanced equation for the decomposition of ammonium nitrate to form molecular nitrogen, molecular oxygen, and water. Hint: Balance oxygen last, since it is present in more than one molecule on the right side of the equation.

It is sometimes convenient to use fractions instead of integers as intermediate coefficients in the process of balancing a chemical equation. For example, consider the reaction of ethane C 2 H 6 with oxygen to yield H 2 O and CO 2 , represented by the unbalanced equation:.

Following the usual inspection approach, one might first balance C and H atoms by changing the coefficients for the two product species, as shown:. A conventional balanced equation with integer-only coefficients is derived by multiplying each coefficient by Finally with regard to balanced equations, recall that convention dictates use of the smallest whole-number coefficients.