The ice cube OR the puddle of water formed from it?

Prelab Title: The Mass of Dissolved Salt Purpose: To determine if a change in mass occurs when salt dissolves in water. Hypothesis: If, then…. WHY? Materials: salt (NaCl) water vial weighing paper paper towel balance

Procedure: 1.Fill vial 1/3 full of water. 2.Get a square of weigh paper and fold it into fourths. 3.Mass the square of weigh paper on digital scale. 4.Using the spatula/spoon, slowly add 0.50g – 1.00g of salt onto the piece of weighing paper. 5.Place the vial containing the water on the balance with the weighing paper and salt. Record the mass. 6.Pour the salt into the vial containing the water. (Be careful not to spill any salt). 7.Swirl gently. Be careful not to spill any water 8.Mass the vial with the salt water and the weighing paper. Record the mass. 9.Take salt water to back sink. CLEAN AND DRY IT!!!!

DATA TABLE Mass of system before dissolving _______g Mass of system after dissolving_______g Change in mass (  _______g “System” is made of _______, _______, ________, and _________. Calculation:  = (Mass after) – (mass before) = m f - m i

Class Data Table (B) #  mass (g) #  mass (g)

Class Data Table (C) #  mass (g) #  mass (g)

Class Data Table (A) #  mass (g) #  mass (g)

Qualitative Data (Observations) You should have AT LEAST three…

Research Questions w/ Answers

Conclusion To determine if there is a change in mass when salt dissolves in water, I…(Don’t forget to tell me if there is a mass change)

What has the greater mass? The bag before the reaction of vinegar + baking soda OR after the reaction?

We’ve talked about changes in matter… The evaporation of a puddle of water Rust forming on a metal fence PHYSICAL CHEMICAL

How did scientists come up with this law? Just like we did with the vinegar and baking soda in a bag! They measured the mass of the reactants (vinegar and baking soda) and then, after the reaction took place, they measured the mass of the products (reactants + carbon dioxide)

The Law of Conservation of Matter During a chemical reaction, matter cannot be created or destroyed. Even though the matter may change from one form to another, the same number of atoms exists before and after the change takes place!

Since the overall mass of the matter does not change… Mass of Reactants Mass of Products

An Example of the L.C.M. lead nitrate potassium iodide Test tube containing lead nitrate is placed upright in a flask that contains potassium iodide. What are these? REACTANTS! They don’t mix!

A stopper is put in place to create a closed system – an environment where matter cannot enter or escape. The mass of the system is found.

After the mass is found, the system is turned upside down so the lead nitrate can mix with the potassium iodide. They create lead iodide and potassium nitrate.

Although the matter changed in form, the total mass of the system remains unchanged.

The Formation of Rust Iron Hard, gray-colored metal Rust Flaky, orange-red solid

When iron reacts with oxygen in the air, they form rust or IRON OXIDE. This is written as: Iron + Oxygen Iron Oxide

Determining the Mass of Reactants and Products REMEMBER: The mass of the reactants is always equal to the mass of the products. Mass of Reactants Mass of Products

Example: Tin Fluoride Tin + hydrogen fluoride -> tin fluoride + hydrogen What’s the total mass of the reactants? g So what should the mass of the products be? g g g

Total Mass of Reactants: g Tin + hydrogen fluoride -> tin fluoride + hydrogen If we know the mass of the tin fluoride, can we figure out how much hydrogen was produced? Subtract the mass of one product from the total mass g2.01 g

ANY QUESTIONS?

What is the final mass of the ice?