In order to calculate the energy required, we must first know the specific heat capacity, or the amount of energy required to raise the temperature of a unit mass of substance by 1 degree Celsius, of water. This, at 1 atm pressure, is 4.18 joules per gram.
Next, we use the formula:
Q = mcΔT, where Q is the energy, m is the mass, c is the specific heat capacity and ΔT is the change in temperature.
Q = 435 * 4.18 * (100 - 25)
Q = 136.4 kJ
Answer : 21.12 g
explanation :
- A limiting reactant is the substance that is totally consumed when the chemical reaction is complete and the reaction cannot continue without it.
- This is a limiting reactant problem because the amount of product (CO2) formed is limited by this substance (either O2 or C3H8).
- We can predict the limiting reactant by calculating number of mole for all reactants;
n (C3H8) = mass/ molar mass = 7/[(12 × 3)+(1 ×8)] = 0.16 mol
n (O2) = mass/ molar mass = 98/(16 × 2) = 3 mol
But we know from this balanced equation that for the reaction to continue, for (n) of propane there must be (5n) of oxygen. Clearly we have more oxygen than required for the reaction to continue as
[ 3 O2 mol > (0.16 propane mol × 5) . Hence, the limiting reactant is propane.
- Using cross multiplication,
0.16 mol propane → 1 mol propane
? → 3 mol CO2
So (n) of CO2 produced = 0.16 × 3 / 1 = 0.48 mol ,
And mass of CO2 produced = n × molar mass = 0.48 × [12 + (16 ×2)] = 21.12 g..
(4)2-8-7-1
The maximum number of electrons in the second two shells is 8, but since there is 7 in the third she'll and 1 in the fourth, that means that one electron was moved to the last shell, putting the atom in the excited state.
Mixing calcium carbonate and HCl.
Heating copper sulfate pentahydrate.
Mixing potassium iodide and lead nitrate.
Combining magnesium and hcl.
Burning the candle.
Let's look at the available options and see what are chemical changes and what are physical changes. As a side note, line breaks, capitalization, and punctuation are VERY important. I spent almost as much time attempting to actually figure out what your options were as I spent in distinguishing between what were chemical reactions and physical changes.
Crushing calcium carbonate.
* This is a mere physical change. You start with large pieces of calcium carbonate and end up with smaller pieces. So this is a bad choice.
Mixing calcium carbonate and HCl.
* This is a chemical reaction where the calcium carbonate and hydrochloric acid react with each other and produce carbon dioxide plus other compounds. So this is a good choice.
Boiling water.
* Another physical change from liquid to vapor. You can cool down the resulting vapor and end up with the original water. So this is a bad choice.
Heating copper sulfate pentahydrate.
* This is a chemical change in that you're converting CuSO4 . 5H2O(s) into CuSO4 and H2O. So this too is a good choice.
Separating iron filing and sulfur.
* You start out with iron filings and sulfur and end up with iron filings and sulfur. Things are a bit more orderly, but no chemical reactions have occurred. So this is a bad choice.
Mixing potassium iodide and lead nitrate. * You start with 2 white solids and upon mixing them, you get a yellow solid.
A chemical reaction has occurred. So this is a good choice.
Combining magnesium and hcl.
* When you combine these two items, you get hydrogen gas as a product. So you have a chemical reaction. And this is a good choice.
Burning the candle.
* Another chemical reaction. The wax combines with the oxygen in the air and produces water vapor and carbon dioxide. So this is a good choice.
Answer:
copper
Explanation:
These are usually copper wires with no insulation. They make the path through which the electricity flows. One piece of the wire connects the current from the power source (cell) to the load