# Problem Solving Rubric (UDRSS)

As derived by the OHHS 2006 Chemistry Collegial team
Weight Category Description
1 Units Units are used correctly throughout the problem.
1 Data All known and unknown variables are listed. When appropriate, a sketch of the physical situation that shows all elements involved in the problem is included.
1 Relationship The correct function, equation, or definition is identified to connect known variables to unknown variables.
1 Substitute All symbols are replaced with known values
1 Solve Numerical values are correct.

## Sample problem 1:

Find the velocity of a car that travels 180 miles in 4 hours.

1. Units: Does every number in the problem below have the appropriate units?
2. Data
• Distance = 180 miles
• Time = 4 hours
3. Relationship: Velocity = Δ distance / Δ time
4. Substitute: Velocity = 180 miles / 4 hours
5. Solve: Velocity = 45 miles/hr

## Sample problem 2:

Pure silver (Ag) has a density of 10.5 g/ml. A 5.25 gram sample of silver is placed into a graduated cylinder that contains 11.2 ml of water. What will the final volume of the water read? 1. Units
• Does every number in the problem below have the appropriate units?
2. Data
• Silver density = 10.5 g/ml
• Silver sample = 5.25 g
• beginning water volume = 11.2 ml
3. Relationship
• Final volume = initial volume + volume of silver
• density = mass / volume
• Solving d=m/v for volume:     v = m / d
4. Substitute
• final volume = 11.2 ml + (5.25g / 10.5 g/ml)
• final volume = 11.2 ml + 0.5 ml
5. Solve
• final volume = 11.7 ml