Chemistry NCFE 2018-19 #29-40

Front

What is the effect of temperature on the concentration of products in a chemical reaction?

Back

Increasing temperature generally increases the concentration of products due to higher kinetic energy, leading to more frequent collisions between reactant molecules.

Front

What is a chemical reaction?

Back

A chemical reaction is a process in which substances (reactants) are transformed into new substances (products) with different properties.

Front

What does it mean when a substance feels slippery and turns red litmus paper blue?

Back

It indicates that the substance is likely a base, as bases feel slippery and turn red litmus paper blue.

Front

How do you calculate the number of particles in a given number of moles?

Back

Use Avogadro's number (6.022 × 10²³ particles/mole). For example, 2.50 moles of O₂ = 2.50 × 6.022 × 10²³ = 1.51 × 10²⁴ particles.

Front

What is Le Chatelier's Principle?

Back

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change.

Front

What happens to a reaction at equilibrium when heat is added?

Back

If heat is added to an exothermic reaction at equilibrium, the reaction will shift to the left (toward the reactants) to absorb the excess heat.

Front

What is the difference between a physical change and a chemical change?

Back

A physical change alters the form of a substance but not its chemical composition, while a chemical change results in the formation of new substances.

Front

What is the significance of the pH scale?

Back

The pH scale measures the acidity or basicity of a solution, with values below 7 indicating acidity, 7 being neutral, and above 7 indicating basicity.

Front

What is the role of catalysts in chemical reactions?

Back

Catalysts speed up chemical reactions by lowering the activation energy without being consumed in the process.

Front

What is Standard Temperature and Pressure (STP)?

Back

STP is defined as 0 degrees Celsius (273.15 K) and 1 atmosphere of pressure, used as a reference point for gas calculations.