En+Ping


 * __Endothermic or Endothermic__**


 * Introduction**

Some reactions absorb heat and others release heat. The two types of reactions are endo and exo; entering and exiting. In exothermic reactions the temperature goes up, in endothermic reactions the temperature goes down. In this experiment, various reactions are examined. Temperatures are measured by a thermometer to decide whether a particular reaction is exothermic or endothermic.

Sodium hydroxide solution + dilute hydrochloric acid Sodium hydrogen carbonate solution + hydrochloric acid Copper(II) Sulfate solution + Magnesium powder (10g 100mL Mg=5g 10s) Dilute sulfuric acid + magnesium ribbon (50mL 1g Mg ribbon 1.0M 0.1M)
 * Materials:**


 * Images of Chemical Compounds**



What to record
hydrochloric acid || 20.2 degrees || increase to 24.8 degrees || Exothermic || hydrochloric acid || 20.7 degrees || decrease to 16.1 degrees then rose up gradually || Endothermic || Magnesium powder || 19.6 degrees || increase to 63.0 degrees || Exothermic ||
 * **Reaction** || **Temperature before mixing/°C** || **Temperature after mixing/°C** || **Exothermic or endothermic** ||
 * Sodium hydroxide solution +
 * Sodium hydrogen carbonate solution +
 * Copper(II) sulfate solution +
 * Dilute sulfuric acid + magnesium ribbon || 20.6 degrees || Increase to 21.4 degrees || Exothermic ||


 * Procedure**

1. Use the apparatus as shown. 2. Put 10 cm3 of sodium hydroxide solution in the beaker, record the temperature then add 10 cm3 of dilute hydrochloric acid, stirring with the thermometer. Record the maximum or minimum temperature. 3. Repeat the procedure for the following reactions: (a) sodium hydrogen carbonate solution and citric acid; (b) copper(II) sulfate solution and magnesium powder; and (c) dilute sulfuric acid and magnesium ribbon.

Questions
1. The first reaction is between an acid and an alkali, what do we call this type of reaction? 2. Which gas is given off when sodium hydrogen carbonate reacts with hydrochloric acid? 3. Which reactions are exothermic and which are endothermic? 4. Why have the atoms in each solution reacted this way? 5. How do modern scientists measure the distance between one molecular atom and another? 6. Does this relate to atoms having negative and positive charges? __**Relationships to atoms and molecules**__ The experiments relates to atoms and molecules because this shows how the molecules and atoms in a reaction are constantly moving. Another way of thinking this is bond breaking and bond making. The sum of all kinetic and potential energies of a substance is known as enthalpy (H). If in a reaction molecule A becomes molecules B and C, and if molecule A has more energy that both B and C combined, then the excess energy will be released into the environment. The environment becomes hotter; we have an exothermic reaction If substance A must take energy away from the environment in order to form product D, then the reaction is said to be endothermic, and the victimized environment will feel colder after the reaction. All types of acids produce hydrogen ions. pH is the measurement of the concentration of hydrogen ions.Water could also be considered as an acid because it seldomly produces hydrogen ions, the chemical compositions of water is H2O which means that inside a bottle of water there could be atoms that are losing or gaining one or more electrons changing the chemical compositions into H30 but this only occurs really rarely when the water molecules collide. A picometer is a trillionth of a meter. In one of the pictures shown distance of one atom and another is measured with great accruacy as picometers was shown to be measured to the tenth digit. __**Question 1**__- The acid-alkali reaction is called an acid-base reaction or a neutralization reaction in which the chemical formula of a mixture is separated.
 * Ion-** a atom or chemical that has gained or lost one ore more electrons causing it to have a positive and negative charge.
 * -Acids**
 * Picometer**__(pm)__