Science, Tech, Math › Science 10 Test Questions on Balancing Chemical Equations Share Flipboard Email Print Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Todd Helmenstine Todd Helmenstine is a science writer and illustrator who has taught physics and math at the college level. He holds bachelor's degrees in both physics and mathematics. our editorial process Todd Helmenstine Updated January 05, 2019 Balancing chemical equations is a basic skill in chemistry. This collection of 10 chemistry test questions tests your ability to balance a chemical reaction. These equations will be balanced for mass. Other tests are available if you're practicing balancing equations for both mass and charge. Question 1 Steve McAlister / Getty Images __ AgI + __ Na S + __ NaI Question 2 __ Ba Question 3 __ CaCl + __ NaCl Question 4 __ FeS + __ O Question 5 __ PCl 5234 + __ HCl Question 6 __ As + __ NaOH → __ Na Question 7 __ Hg(OH) O Question 8 __ HClO Question 9 __ CO + __ H O Question 10 __ KClO + __ KCl Answers 1. 2 AgI + 1 Na2S → 1 Ag2S + 2 NaI2. 1 Ba3N2 + 6 H2O → 3 Ba(OH)2 + 2 NH33. 3 CaCl2 + 2 Na3PO4 → 1 Ca3(PO4)2 + 6 NaCl4. 4 FeS + 7 O2 → 2 Fe2O3 + 4 SO25. 1 PCl5 + 4 H2O → 1 H3PO4 + 5 HCl6. 2 As + 6 NaOH → 2 Na3AsO3 + 3 H27. 3 Hg(OH)2 + 2 H3PO4 → 1 Hg3(PO4)2 + 6 H2O8. 12 HClO4 + 1 P4O10 → 4 H3PO4 + 6 Cl2O79. 8 CO + 17 H2 → 1 C8H18 + 8 H2O10. 10 KClO3 + 3 P4 → 3 P4O10 + 10 KCl Tips for Balancing Equations When balancing equations, remember the number of atoms of each element needs to be the same on both sides of the equation.The coefficients (numbers in front of a species) are multiplied by every atom in that chemical.The subscripts are multiplied only by the affected atom.To start balancing, begin with less-common elements, like metal atoms or oxygen, and leave hydrogen atoms for last (they are usually the easiest to balance.Be sure to check your work! Make a tally of all the atoms of each element on each side of the equation. Are they the same? Good! If not, go back and rework the coefficients and subscripts.Although this test did not cover it, it's good practice to indicate the state of matter for each chemical species (s for solid, l for liquid, g for gas, and aq for a species in aqueous solution). Cite this Article Format mla apa chicago Your Citation Helmenstine, Todd. "10 Test Questions on Balancing Chemical Equations." ThoughtCo, Aug. 25, 2020, thoughtco.com/balancing-chemical-equations-test-questions-604109. Helmenstine, Todd. (2020, August 25). 10 Test Questions on Balancing Chemical Equations. Retrieved from https://www.thoughtco.com/balancing-chemical-equations-test-questions-604109 Helmenstine, Todd. "10 Test Questions on Balancing Chemical Equations." ThoughtCo. https://www.thoughtco.com/balancing-chemical-equations-test-questions-604109 (accessed January 27, 2021). copy citation