A student heats 0.5978 g of iron with 0.3541 g of sulfur. She reports that she obtains 0.8456 g of iron sulfide and recovers 0.1233 g of unreacted sulfur. Show by calculation whether or not her results obey the law of conservation of mass.
mass before reaction

Enter a number with the correct number of significant figures.

1 g
mass after reaction

Enter a number with the correct number of significant figures.

2 g

Give the period number and group number for the element whose atoms have the following electron configurations.

(a) 1s22s2 period number Answer is not case sensitive. 1 group number Answer is not case sensitive. 2	(b) 1s22s22p63s23p4 period number Answer is not case sensitive. 3 group number Answer is not case sensitive. 4	(c) 1s22s22p3 period number Answer is not case sensitive. 5 group number Answer is not case sensitive. 6
(d) 1s22s22p63s1 period number Answer is not case sensitive. 7 group number Answer is not case sensitive. 8	(e) 1s2 period number Answer is not case sensitive. 9 group number Answer is not case sensitive. 10	(f) 1s22s22p63s23p2 period number Answer is not case sensitive. 11 group number Answer is not case sensitive. 12

Calculate the molarity of each of the following solutions.

(a) 1.67 mol of H₂SO₄ in 3.00 L of solution

Enter a number with the correct number of significant figures.

1 M
(b) 2.67 mol of C₂H₅OH in 13.2 mL of solution

Enter a number with the correct number of significant figures.

2 M

Identify the oxidizing agent and the reducing agent in each reaction. (Type your answer using the format CO2 for CO₂.)

(a) Cl₂ + 2 KBr 2 KCl + Br₂
oxidizing agent

Answer is case sensitive.

1
reducing agent

Answer is case sensitive.

2
(b) 2 SO₂ + O₂ 2 SO₃
oxidizing agent

Answer is case sensitive.

3
reducing agent

Answer is case sensitive.

4

Select four cations present in groundwater.

Select three anions present in groundwater.