1. Chemical Formulas and Equations Test Review H2OH2O2H 2 + O 2  2H 2 O

2. Which is an example of a compound? NaCL A compound has….. 2 or more atoms AND they need to be different. Na 2Na NaCl Na₂

3. Which is not a molecule? Na Na is just an element (1 atom). Molecules have 2 or more atoms. H₂O NaCl Na Na₂

4. How many atoms are in Na ₂ SO ₄ ? 7 Na = 2 S = 1 O = 4

5. How many atoms are in C 6 H 12 O 6 ? 24 Na = 6 S = 12 O = 6

6. Which is an example of a element? O O is just an element (1 atom). H₂ O SO₄ C₆H 12 O₆

7. A molecule has 3 atoms of hydrogen (H) and 2 atoms of sulfur (S), what’s the formula? H₃S₂

8. Four molecules of 2 atoms of hydrogen (H) and 2 atoms of oxygen (O), what’s the formula? 4H₂O₂

9. How many atoms are in 2CaCl ₂ ? 6 Ca = 2 Cl = 4

10. What’s the ratio of calcium (Ca) to chlorine (Cl) in CaCl ₂ ? 1 to 2 Ca = 1Cl = 2

11. What’s the ratio of oxygen(O) to hydrogen (H) in H ₂ O? 1 to 2 O = 1H = 2

12. What’s the ratio of oxygen (O) to sulfur (S) in 2SO ₄ ? 8 to 2 2S 1 O 4 O = 8S = 2

13. What is the formula for the model below. 4H₂O₂ = Hydrogen = Oxygen

14. The coefficient in 7H 2 CO 3 tells that there is… 7 molecules of H 2 CO 3

15. The coefficient in 6LiNO 3 tells that there is… 6 molecules of LiNO 3

16. What’s the ratio of lithium (Li) to oxygen (O) in 3LiNO 3 ? 3 to 9 3Li 1 N 1 O₃ Li = 3O = 9

17. What’s the coefficient of 4MgCl ₂ ? 4 The coefficient is the big number in front of the chemical formula. It tells the number of molecules there are.

18. What is the subscript(s) of 4MgCl ₂ ? 2 The subscripts is the small number behind the chemical symbol. It tells the number of atoms there are for that element.

19. What’s the ratio of hydrogen (H) to zinc (Zn) in 2ZnH ₂ ? 4 to 2 2Zn 1 H 2 H = 4Zn = 2

20. What is the subscript(s) of 7Ba ₃ P ₂ ? 3 and 2 The subscripts is the small number behind the chemical symbol. It tells the number of atoms there are for that element.

21. What is the formula for the model below. 3FeH₃ = Iron (Fe) = Hydrogen (H)

22. What does the subscript tell you? The number of atoms of that element.

23. What is the Law of Conservation of Mass? Mass cannot be lost or gained OR Mass cannot be created or destroyed.

24. What are the product(s)? 2H 2 O 2 → 2H 2 O + O 2 The yield sign always points to the product.

25. What are the product(s)? 3Ca + N 2 → Ca 3 N 2 The yield sign always points to the product.

26. What are the reactant(s)? 2Li + F 2 → 2LiF The yield sign always points to the product.

27. What are the reactant(s)? Al 2 O 3  4Al + 3O 2 The yield sign always points to the product.

28. What are the product(s)? 2NaOH + H 2  2Na + 2H 2 O The yield sign always points to the product.

29. Does this chemical equation follow the Law of Conservation of Mass? Al + S → Al 2 S 3 No 1 = Al = 2(Not Equal) 1 = S = 3(Not Equal)

30. Does this chemical equation follow the Law of Conservation of Mass? HgO → Hg + O 2 No 1 = Hg = 1(Equal) 1 = O = 2(Not Equal)

31. Does this chemical equation follow the Law of Conservation of Mass? 2K + S → K 2 S Yes 2 = K = 2(Equal) 1 = S = 1(Equal)