Lesson 7: Chemical Equations

This set of flashcards addresses key concepts from the lecture on chemical equations, including types of reactions, balancing equations, and the underlying principles of chemical reactions.

What is a chemical reaction?

A process where substances (reactants) are transformed into new substances (products) through chemical changes.

What does the Law of Conservation of Matter state?

Atoms are rearranged in a chemical reaction, but no atoms are lost or gained.

What is a chemical equation?

A symbolic representation of a chemical reaction, including the formulas of reactants and products.

What do the symbols (s), (l), (g), and (aq) represent in a chemical equation?

(s) – solid; (l) – liquid; (g) – gas; (aq) – aqueous (dissolved in water).

What must each side of a chemical equation have?

The same number and type of atoms.

What are coefficients in a chemical equation?

Numbers used to balance the equation by multiplying the number of molecules.

What should you never change when balancing chemical equations?

Do not change the subscripts of compounds.

What is the first step in balancing a chemical equation?

Write the unbalanced equation using the correct chemical formulas for all reactants and products.

What should be balanced one element at a time?

Chemical equations.

What is a major observable sign of a chemical reaction?

Color change, gas production, or formation of a precipitate.

What type of reactions involve two or more substances combining to form one product?

Synthesis (Combination) reactions.

Define a decomposition reaction.

A reaction where a single compound breaks down into two or more simpler substances.

What happens in a single-displacement reaction?

One element replaces another in a compound.

What occurs during a double-displacement reaction?

Two compounds exchange ions to form two new compounds.

What type of reaction typically involves hydrocarbon and oxygen?

Combustion reaction.

What is the general formula for a synthesis reaction?

A + B → AB.

What is the general formula for a combustion reaction?

Hydrocarbon + O2 → CO2 + H2O + energy.

What must be done to predict products in a double replacement reaction?

Determine the cations and anions of each aqueous reactant and exchange the ions.

How is a balanced equation defined?

Equal numbers of atoms for each element are represented on both the reactant and product sides.

What is an example of a balanced equation for combustion?

C3H8(g) + 5O2(g) → 3CO2(g) + 3H2O(g).

What is the importance of coefficients being whole numbers in balancing equations?

They must accurately reflect the number of molecules in a reaction.

What is one approach to balancing equations involving polyatomic ions?

Treat the polyatomic ions as a single unit if they appear on both sides.

What affect does a coefficient have on a molecule?

It multiplies the entire molecule.

What should always be checked after balancing equations?

Ensure that there are the same number of atoms on both sides.

Why is it important to balance chemical equations?

To satisfy the law of conservation of mass.

What are examples of chemical reaction signs?

Color changes, gas production, and precipitate formation.

What type of reaction is represented by the equation 2Na + Cl2 → 2NaCl?

Synthesis reaction.

What is demonstrated by the equation Zn + CuSO4 → ZnSO4 + Cu?

Single displacement reaction.

What is an example of double displacement reaction?

AgNO3 + NaCl → AgCl + NaNO3.

What does __ C4H10 + __ O2 → __ CO2 + __ H2O represent?

A combustion reaction requiring balancing.

What signifies a combustion reaction in terms of products?

Produces water and carbon dioxide and releases energy.

What is the balanced equation when Ca(NO3)2 and Na3PO4 react?

3Ca(NO3)2 + 2Na3PO4 → Ca3(PO4)2 + 6NaNO3.

Which chemical reaction involves oxidation of metallic elements?

Single-displacement reactions.

How does one balance the equation: NH3 + H2SO4 → (NH4)2SO4?

By adjusting coefficients accordingly.

What do you observe in a decomposition reaction such as 2HgO?

It breaks down into 2Hg + O2.

What should you do with fractions during the balancing process?

Use them during calculations but convert to whole numbers at the end.