Balancing Chemical Equations

Which balances the equation Mg + O2→ MgO?

2Mg + O2 → 2MgO

Lana balanced an equation so that the result was 2C2H3Br + 5O2 → 4CO2 + 2H2O + 2HBr. Which most likely represents the starting equation?

C2H3Br + O2 → CO2 + H2O + HBr

The equation below shows a general equation for a reaction, and the amounts of the substance are written underneath. AB + CD → AC + BD (15 g) (?) (?) (10 g) The total mass of the products is 50g. Which best completes the other two amounts?

The amount of CD is 35 g, and the amount of AC is 40 g.

Balanced chemical equations express the law of conservation of

mass

If the mass of the products measured 120 g, what would be the mass of the reactants?

120 g

The amount of oxygen in the reactants is 4 atoms. In the products, the oxygen is distributed to water (H2O) and O2 gas. Which coefficients would be placed in front of water and oxygen?

2 in front of water and 1 in front of oxygen

The equation below is for potassium oxide. 4K + O2→ 2K2O The ratio of atoms of potassium to ratio of atoms of oxygen is .

2.1

One half of a balanced chemical equation is shown. 3Mg(OH)2 + 2H3PO4 Which lists the numbers of each atom the other half of the equation would contain?

3 Mg, 2 P, 14 O, 12 H

Substances A and B react in a ratio of A + B → AB. Colin was combining substance A and substance B to form substance AB. He added 10 g of substance A and 45 g of substance B. How much of substance AB would Colin make?

55 g

The equations are not balanced. Which equation would have the same coefficients in the same order as 2CO2 + 3H20 → C2H6O + 3O2?

Al + FeO → Al2O3 + Fe

Lexi is balancing equations. She is finding one equation to be very difficult to balance. Which explains how to balance the equation ZnSO4 + Li2CO3 → ZnCO3 + Li2SO4?

Atoms in the equation are already in balance.

Which equations are balanced? Check all that apply.

C3H8 + 5O2→ 4H2O + 3CO2 Zn + 2HCl → ZnCl2 + H2 3Ca(OH)2 + 2H3PO4→ Ca3(PO4)2 + 6H2O 4Al + 3O2→ 2Al2O3

Plants use sunlight as energy to convert carbon dioxide and water into glucose and oxygen. Which best describes the reaction?

The law of conservation of mass indicates the same amount of carbon will be found in the reactants as in the products.

Which best describes the law of conservation of mass?

The mass of the reactants and products is equal and is not dependent on the physical state of the substances.

Hydrochloric acid and sodium hydroxide can be combined in equal ratios to form sodium chloride and water. Which best explains the reaction?

The total volume produced by combining hydrochloric acid and sodium hydroxide will result in the same volume of sodium chloride and water.

Which is the balanced equation for V2O5 + CaS → CaO + V2S5?

V2O5 + 5CaS → 5CaO + V2S5

If the number of atoms in the reactants equals the number of atoms in the products, the equation is

balanced

Akia is balancing the equation Na + H2O NaOH + H2. He tries to find the coefficients that will balance the equation. How could he find the correct coefficients?

by counting up each individual atom and make sure the atom numbers are the same in the reactants and the products

Charlie is balancing an equation. She has identified the atoms and counted the number of each in the reactants and products. What would Charlie adjust to make the number of atoms in the reactants the same as the number of atoms in the products?

coefficients

Kiley wants to balance the equation H2 + N2 → NH3. Which would be her first step in balancing an equation?

creating a chart that shows the number of atoms in the reactants and products