Chemistry - Ch 1 : Chemical Reactions and Equations

Comprehensive fill-in-the-blank practice cards covering key concepts, equations, indicators, reaction types, and real-world phenomena from the Chemical Reactions and Equations lectures.

A process in which the final state of the substance is different from the initial or original state is known as __________.

change

Changes are classified as physical or chemical based on whether there is a change in __________ composition.

chemical

A transformation in which shape, size, or physical state changes without any change in chemical composition is called a __________ change.

physical

The process of chemical change in which new substances are formed with a different chemical composition is called a __________.

chemical reaction

When colorless barium chloride reacts with colorless sodium sulphate, a white insoluble precipitate of __________ is formed.

barium sulphate

A reaction where energy is released, generally as heat, causing the temperature to rise is classified as an __________ reaction.

exothermic

A reaction in which energy is absorbed, causing the temperature to decrease, is classified as an __________ reaction.

endothermic

When strongly heated in the presence of oxygen, magnesium ribbon burns with a dazzling white flame to form white __________ powder.

$$MgO$$

Before burning, magnesium ribbon is cleaned with __________ to remove the coating of magnesium oxide on its surface.

sandpaper

Eye protection is advised when burning magnesium ribbon because the dazzling white light emits __________ rays.

UV

The substances that undergo a chemical change during a chemical reaction are known as __________.

reactants

The new substances that are formed after a chemical change has taken place are called __________.

products

A chemical equation in which the number of atoms on the reactant side is not equal to that on the product side is called a __________ chemical equation.

skeletal

Chemical equations must be balanced to satisfy the law of conservation of mass, which states that mass can neither be created nor be __________.

destroyed

When balancing equations containing complex groups, such as in the reaction between zinc and phosphoric acid, one should balance the __________ first.

polyatomic ion

To remove the limitations of a balanced chemical equation and make it more informative, one adds the reaction conditions, energy changes, and the __________ of reactants and products.

physical states

A chemical reaction in which two or more elements or compounds react to produce a single product is called a __________ reaction.

combination

The vigorous combination of solid calcium oxide with liquid water produces slaked lime, which has the formula __________.

$$Ca(OH)_2$$

A solution of slaked lime applied to walls reacts with carbon dioxide over 2 to 3 days to produce a shiny finish of __________.

calcium carbonate

A chemical reaction where a single compound breaks down into two or more elements or simpler compounds is called a __________ reaction.

decomposition

Decomposition caused by the application of heat is specifically known as thermolysis or a __________ decomposition reaction.

thermolytic

Heating pale green ferrous sulphate crystals causes them to lose water, and further heating yields sulfur dioxide, sulfur trioxide, and a reddish-brown solid of __________.

$$Fe_2O_3$$

The crackling sound heard during the thermal decomposition of lead nitrate powder is known as __________.

decrepitation

Thermal decomposition of lead nitrate produces a yellow residue of lead oxide, colorless oxygen gas, and brown fumes of __________.

nitrogen dioxide

Photosensitive halides such as silver chloride and silver bromide decompose in the presence of sunlight and are utilized in __________ photography.

black & white

During the electrolytic decomposition of acidified water, combustible hydrogen gas is gathered at the __________.

cathode

To improve the electrical conductivity of water during electrolysis, small amounts of sodium chloride or __________ are added.

$$H_2SO_4$$

Heating sucrose strongly past its melting stage produces water vapor and a solid carbonaceous residue referred to as sugar __________.

charcoal

A chemical reaction where a more reactive element displaces a less reactive element from its solution is termed a __________ reaction.

displacement

When iron nails are placed in a blue copper sulphate solution, the solution turns pale green due to the formation of __________.

$$FeSO_4$$

A chemical reaction in which mutual exchange of cations and anions occurs between two compounds is known as a double displacement or __________ reaction.

metathesis

Mixing aqueous solutions of potassium iodide and lead nitrate yields a precipitate of lead iodide that has a distinct __________ color.

yellow

In terms of hydrogen transfer, the chemical process involving the removal of hydrogen is defined as __________.

oxidation

A chemical substance in a redox reaction that accepts electrons, gets reduced, and oxidises another reactant is termed an __________.

oxidising agent

The slow oxidation of oils and fats in food items that leads to an unpleasant taste and odor is known as __________.

rancidity

To inhibit oxidative rancidity, snack packaging is commonly flushed with unreactive gases such as helium or __________.

$$N_2$$

The protective, impervious green layer formed on the surface of copper due to corrosion is referred to as __________.

patina

Unlike the protective coating on copper, rust formed on iron is brittle and __________, continuously exposing fresh metal to atmospheric degradation.

flaky