Answer:
12.044 X 10^23 molecules of NaOH
Explanation:
because NaOH is an ionic bond, we should be asking how many <em>formula units </em> are in 2 moles of NaOH, there are 0 molecules since NaOH is measured in formula units.
but for the sake of the problem I'll assume NaOH is measured in molecules
for every mol of something there are 6.022 X 10^23 of something of that something.
so there are 6.022 X 10^23 molecules for every mol of NaOH
that means we have 2 X 6.022 X 10^23 molecules in 2 moles of NaOH = 12.044 X 10^23 molecules of NaOH
Heat_1: Get the ice to 0 degrees
Convert 7 kg to grams
7 kg [1000 grams / 1 kg] = 7000 grams
Heat needed to get the the ice from - 9 to 0
deltat = 0 - -9 = 9 degrees
m = 7000 grams
c = 2.1 joules/gram
Heat_1 = m*c*deltat
Heat_1 = 7000 * 2.1 * 9
Heat_1 = 132,300 joules
Heat_2: Melt the ice.
There is no temperature change. The formula is 333 j/gram
Formula: H = mass * constant
H = 7000 g * 333 J / gram
H = 2331000 joules
Heat_3: Total amount of Joules needed.
2331000 + 132300 = 2 463 300 joules
Convert to Megajoules
2 463 300 joules * 1 megajoule / 1000000 = 2.63 megajoules.
<span>All metals have similar properties BUT, there can be wide variations in melting point, boiling point, density, electrical conductivity and physical strength.<span>To explain the physical properties of metals like iron or sodium we need a more sophisticated picture than a simple particle model of atoms all lined up in close packed rows and layers, though this picture is correctly described as another example of a giant lattice held together by metallic bonding.</span><span>A giant metallic lattice – the <span>crystal lattice of metals consists of ions (NOT atoms) </span>surrounded by a 'sea of electrons' that form the giant lattice (2D diagram above right).</span><span>The outer electrons (–) from the original metal atoms are free to move around between the positive metal ions formed (+).</span><span>These 'free' or 'delocalised' electrons from the outer shell of the metal atoms are the 'electronic glue' holding the particles together.</span><span>There is a strong electrical force of attraction between these <span>free electrons </span>(mobile electrons or 'sea' of delocalised electrons)<span> (–)</span> and the 'immobile' positive metal ions (+) that form the giant lattice and this is the metallic bond. The attractive force acts in all directions.</span><span>Metallic bonding is not directional like covalent bonding, it is like ionic bonding in the sense that the force of attraction between the positive metal ions and the mobile electrons acts in every direction about the fixed (immobile) metal ions of the metal crystal lattice, but in ionic lattices none of the ions are mobile. a big difference between a metal bond and an ionic bond.</span><span>Metals can become weakened when repeatedly stressed and strained.<span><span>This can lead to faults developing in the metal structure called 'metal fatigue' or 'stress fractures'.</span><span>If the metal fatigue is significant it can lead to the collapse of a metal structure.</span></span></span></span>
The answer is: The reactants were not heated long enough.
For all chemical reaction some energy is required and that energy is called activation energy (energy that needs to be absorbed for a chemical reaction to start).
Activation energy is the minimum energy colliding particles must have in order to react.
By lowering activation energy, reaction need less heat.
In this example, there is not enough heat.
