Unit 5 Test Physical Science:Balancing , Acids/Bases Half-Life Problems Balance and name the following chemical equations:SHOW ALL woRK OR NO CR EDIT WILL BE GIVEN 1! The five types of reactions are:synthesis, decom position , singe replacer nent, double replacement or combustion. 1 Fe+H_(2)Oarrow Fe_(3)O_(4)+H_(2) 2 H_(3)AsO_(4)arrow As_(2)O_(5)+H_(2)O 3 SiO_(2)+HFarrow SiF_(4)+H_(2)O 4. C_(3)H_(8)+O_(2)arrow CO_(2)+H_(2)O 5 S_(8)+O_(2)arrow SO_(3) Acids /Bases 1. What is the pH value of an acid? 2 . What is the pH value of a base? 3 . What color do acids turn? 4 . What color do bases turn? 5 . What is the pH value of a strong acid? Half-Life Problems:SHOW CHART WITH ALL WORK OR NO CREDIT WILL , BE GIVEN! 1. How many days does it take for 16 g of palladium -103 to decay to 1g?The half-life of palladium -103 is 17 days. 2 . Magnesium -25 has a half-life of 15 hours .How much sodium 1-24 will remain in an 18g sample after 75 hours. 3 . After 42 days a2g sample of sulfur -33 contains only .25g of the isotope. What is the half-life of sulfur-33?

## Balancing Chemical Equations:### **Balancing Chemical Equations**Balancing chemical equations is a process that ensures that the number of atoms for each element is the same on both sides of the equation. This is in line with the Law of Conservation of Mass, which states that matter cannot be created or destroyed in a chemical reaction.## Step1For the first equation, we have . To balance this equation, we need to ensure that the number of atoms for each element is the same on both sides.## Step2For the second equation, , we need to balance this equation as well.## Step3For the third equation, , we need to balance this equation.## Step4For the fourth equation, , we need to balance this equation.## Step5For the fifth equation, , we need to balance this equation.## Acids/Bases:### **Acids/Bases**Acids and bases are two types of chemical substances that have different properties. Acids have a pH value less than 7, while bases have a pH value greater than 7. Acids usually turn red in universal indicator solution, while bases turn blue.## Step6Acids generally have a pH value less than 7.## Step7Bases generally have a pH value greater than 7.## Step8Acids usually turn a red color in universal indicator solution.## Step9Bases usually turn a blue color in universal indicator solution.## Step10The pH value of a strong acid is usually around 1.## Half-Life Problems:### **Half-Life Problems**Half-life is the time required for half of the atoms in a sample to decay. It is used to calculate the time it takes for a substance to decrease by half.## Step11For the first half-life problem, we need to find out how many days it takes for 16g of palladium-103 to decay to 1g. The half-life of palladium-103 is 17 days.## Step12For the second half-life problem, we need to find out how much sodium-24 will remain in an 18g sample after 75 hours. Magnesium-25 has a half-life of 15 hours.## Step13For the third half-life problem, we need to find out the half-life of sulfur-33. After 42 days, a 2g sample of sulfur-33 contains only 0.25g of the isotope.