SKILL BUILDER PAGE 88

 
ACIDIC AND BASIC

https://drive.google.com/open?id=0B7iv3aqF9aB_TEkyc21qU2MzSEk

PH

1. What is PH?

A/ PH is measure of how acids or basic solution is, related to its concentration of hydronium ions and hydroxide ions.

2. What are PH values? Do these values depend on something?  Explain your answers.

A/ The pH scale generally ranges from 0 to 14. more acidic solutions have lower pH values , and a solution with a pH of 0 is highly acids. A solution that has a PH of 7 is neutral. More basic solutions have higher pH values, and a solutions with a pH of 14 is extremely  basic.

The acid solutions have more hydronium ions than hydroxide ions.  Neutral solutions have equal numbers of two ions. Basic solutions have more hydroxide ions than hydronium ions.

3. Check Chart 3.2 about acids and bases.  What can you explain about it?

A/ The strong acids are: Hydrochloric - Sulfuric - Nitric.

The strong bases are: Sodium hydroxide - Potassium hydroxide.

The weak acids are: Acetic - Carbonic – Ascorbic.

The weak bases are: Ammonia - Aluminum hydroxide - Iron (||) hydroxide.

4. What is Neutralization?  Give examples.

A/ is the interaction that occurs between acids and bases in which  the properties of each are canceled out by th other.

Example :

1:  an acid (substances releasing hydrogen ions H), and a base (subtance that releases OH ions) react to form a salt and water.

2: the pH of the neutralization reaction is a neutral ie 7, and the temperature increases ligemene as the reaction occurs.

SKILL BUILDER PAG 80

VARIABLES AND CONTROLS

How did dissolving salt in one beaker affect the water temperature?

Dissolving common salt in water is a process that is not energetically neutral. It ‘takes the electrical energy to break the red salt crystal and the hydrogen bonds between the water molecules. At room temperature, the result is such that the entire process absorbs the energy; the enthalpy of the dissolution of the common salt in water is ΔH ≈ 3.9 kJ mol-1.

The agitation of the water causes an increase in temperature due to the increase of kinetic energy, however, the dissolution of the salt consumes part of the energy generated, so that the temperature of the salt solution is lower than the water alone.

What were the controls? Variables?

The independent variable is the factor that a scientist manipulates to obtain results.

The dependent variable will respond to changes in the independent variable.

Control variables are the things that are kept constant in each test of the experiment.

In this case the independent variable is the dissolution of the salt in water, the dependent variable is the temperature of the water that will change due to the presence of the salt. The control variable is the amount of water added, which is the same from the beginning to the end of the experiment in both beakers.

PRACTICING THE SKILL

1.    Ten grams of sugar dissolves more quickly in a liter of pure,hot,tap wáter tan it does in a liter of pure,cold,tap wáter. List the controls, the independent variable, and the dependent variable.

Controls: Same amount of water, same amount of sugar, both containers are covered.

Independent variables: water temperatures: cold and hot.

Dependent variables: time in which the sugar dissolves.

2.    Identify the dependent variable from the following hypothesis: Of Premium gasoline is more efficient, so it should increase the fuel mileage of our family car.

Dependent variable: family car efficiency

SKILL BUILDER, page 74. COMPARING AND CONTRASTING

COMPARING

CONTRASTING

The mixtures studied are homogeneous, except for cloudy ice cubes with a heterogeneous appearance because the outside of the cube is the first to freeze, and the interior of the water to find its liquid state. In alloys, carbonated-beverage and lasers are not distinguished phases, so they can be considered homogeneous.

The mixtures analyzed are of different composition in the state in which they are, the helium-neon laser is a gaseous mixture, because the elements are in this state. Alloys are solid mixtures (copper-tin), their appearance is totally homogeneous. Ice cubes are liquid-solid mixtures, due to the presence of small particles (corresponding to minerals) found in water. Ginger ale is a carbonated-beverage, so it has a gaseous part and a drink, usually the gas is dissolved in the liquid part, when the solution is in contact with the environment, ie the bottle, the gas escapes from the liquid.

ISA SCIENCE 7 GRADE 


THE NUCLEAR ATOM 


https://drive.google.com/file/d/0B7iv3aqF9aB_dDZRUjBrdHlWbVE/view?usp=sharing

1800 & modern times

                                                     

                                                Energy and types of Energy


Energy is the ability to do some work.We know also that all things around us need energy to move. When we apply a force onto an object, we are using our muscular energy.  There are several types of energy, depending on where they come from: The first one is electrical energy, an example of it is our light bulbs, the tv or the air conditioners we use at home. The second one is heat energy, coming from fire(as an example) or the 90% of the electrical energy that become heat energy in our light bulbs(that's why they are warm when we touch them). When we move objects with our hands, we use our muscles, so it is called: muscular energy! If we imagine we are doing some sport at the park and it is very sunny, we can understand how Solar Energy does affect us, and how they can be stored into solar panels. The last two types of energy are: hydel energy, coming from moving water and wind  energy(come from moving air and obtained with windmills).