Understanding Chemistry: From Atoms to Reactions

What does chemistry help us understand about the world?

• Only the largest structures in the universe

• Only the atomic structure of elements

• Only the behavior of massive objects

• Both the tiniest particles and the largest structures

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Why do chemists need to understand the mass of substances?

• To predict how substances will react

• To increase the volume of substances

• To make substances lighter

• To change the color of substances

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What is the primary purpose of stoichiometry in chemistry?

• To discover new particles

• To change the properties of elements

• To measure chemicals in reactions

• To create new elements

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Why was carbon-12 chosen as the standard for atomic mass units?

• Because it bonds with many elements

• Because it is the lightest element

• Because it only has one isotope

• Because it is rare and valuable

What does one mole of any substance contain?

• 6.022 x 1023 molecules

• 12 grams of substance

• 1.008 grams of substance

• 55.85 grams of substance

How is the molar mass of a compound calculated?

• By adding the atomic numbers of its elements

• By measuring its volume

• By counting the number of molecules

• By adding the molar masses of its component elements

What is the significance of Avogadro's number in chemistry?

• It is used to measure time in chemical reactions

• It represents the boiling point of water

• It determines the color of substances

• It is the number of atoms in 12 grams of carbon-12

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What does the molar mass of an element equal?

• Its atomic number in grams

• Its relative atomic mass in grams

• Its density in grams per cubic centimeter

• Its volume in liters

What is necessary to balance a chemical equation?

• Equal number of molecules on both sides

• Equal number of atoms of each element on both sides

• Equal volume of reactants and products

• Equal mass on both sides

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How can stoichiometry be applied in real life?

• To calculate specific masses of reactants and products

• To determine the color of a compound

• To calculate the speed of a chemical reaction

• To predict the temperature of a reaction