Chemistry

  Strong and weak acids Strong acids: Acids contain hydrogen. Some acids are better at producing H + (aq) ions than others. These are called strong acids. Strong acids split up (dissociate) almost completely in water. Weak acids: However, weak acids reach dynamic equilibrium. The acid molecules split up, just like a strong acid. But at the same time, the H + ions and OH - negative ions that are made join up again. They form the original acid molecules

Define Monocot, Dicot and Conifer.  Monocot: A monocot produces seeds with a single cotyledon. Leaves of monocot plants show a parallel vein pattern. Dicot: A dicot produces seeds with two cotyledons. Leaves of dicot plants show a branched vein pattern. Conifer: Is a gymnosperm, a plant that has seeds but not flowers.

 Revision work for G-8 Chemistry Chapter 15 and 16 Question 1                    Exothermic reactions give out energy. T Endothermic reactions take in energy. T In exothermic reactions, the temperature goes down, F Δ H is negative for an endothermic reaction. F Breaking bonds requires energy. T Whenever chemicals react, we get a transfer of energy. T Food is the fuel for our bodies. T   Question 2                    1 You need 3 things to make a fire A. Fuel   B.  heat C. oxygen All of them 2 Fuels store ------------ energy. a)P.E    b)K.E    d)none of them c)Chemical 3 The gas we burn in a Bunsen burner is usually methan a)CH        b)CH 2        c)CH 3 d)CH 4 4 Therefore we use a copper beaker (called a---------) a)Thermometer    c)pH meter    d)barometer b)Calorimeter 5 Some reactions take in heat from their surroundings. These are called ----------------------reactions. b)Exothermic             c)both          d)none of them a)endo

  Factors affecting the position of equilibrium The position of equilibrium shifts to try to cancel out any changes you introduce. Changing concentrations: Increase the concentration of a reactant. This will make the forward reaction go faster for a while, until we reach equilibrium again.  We have added more to the left-hand side, so the equilibrium shifts to the right, as if to remove it. Changing temperature: The position of equilibrium shifts to reduce the temperature. Changing pressure: Changing the pressure can also affect a mixture at equilibrium. However, there must be different numbers of gas molecules on either side of the equation.  If you increase the pressure, the equilibrium shifts to try to reduce it again. Q: Write any two factors affecting the position of equilibrium. Ans: Concentration,  temperature and pressure.

What is Embryo, Seed coat and Germination? Embryo: An embryo is the beginning of a new offspring. As it grows, the embryo is packaged insid e a seed. seed coat: The entire seed is surrounded by a tough outer covering called a seed coat. Germination: The d evelop ment of a seed into a new plant.

 Revision work Chapter 1, 2 and 3 Chemistry G-7 True and False. The particles move from an area of low concentration to an area of high concentration is called diffusion. F Molecules are groups of 2 or more atoms bonded together. T Elements contain only one type of atom. T Compounds contain 2 or more types of atom. T Chemists use a kind of short-hand to describe molecules. It's called the symbol. F Fill in the blanks. The particles move from an area of ---------------------- concentration to an area of low concentration is called diffusion. High Good scientists make sure their data provides evidence that is reliable and ---------------------------- . valid You can use existing theories to explain----------------------------. Ideas -----------------------tells us how near the true reading your measurement is. Accuracy I'm Elvis the Electron and I'm pretty quick, I fly round the nucleus at a fair old lick! The protons and I, we tend to attract, I'm -------

What is Plant Life cycles and Alternation of Generation? Define Pollination and Pollen.  Life cycle: A life cycle is a  series of differing stages of development.  Plant Life cycles: Plant life  cycles include both an asexual and a sexual stage.  Alternation of Generation: This  process of alternating between asexual and sexual  reproduction is called an alternation of generations. Pollination: Is the transfer of pollen from the stamen to the pistil. Pollen: Is a yellow powder that contains sperm cells.

Group 1 - The alkali metals: They are too reactive. sodium, and the other alkali metals, are unusual metals. They have low melting points and are very soft. For metals, they also have very low densities. Compounds formed by Group 1  metals are usually white solids (that dissolve in water to form colorless   solutions). Q: Why potassium float on water? Ans: Due to low density. Q: What patterns can you see going down the group? Ans: Atomic number increase while melting and boiling point decrees down the group. The alkali metals get more reactive going down the group.

 What is life cycle and parts of a flower? What is life cycle? Lif e cycle is a ser i es of differing stages of development. What are the parts of a flower? A complete flower has all of the four main parts: petals, sepals, stamens, and pistils.