Answer:
Explanation:
In this chemistry lab, students investigate how to build and launch a simple rocket that uses hydrogen and oxygen gases that will be mixed to propel the rocket (large bulb plastic pipette). Students will understand the principles of combustion reactions, kinetics, stoichiometry of reactions, activation energy, explosive mixtures, rocketry, and different types of chemical reactions. Students will explore and determine the proportions of hydrogen and oxygen mixture that will achieve the best launch results. Students will compare the balanced chemical reaction of hydrogen and oxygen with their lab results; students should discover that the optimal distance occurs when the mixture of hydrogen and oxygen is two to one hydrogen, oxygen mixture ratio and this can be determined theoretically from the balanced chemical reaction equation. Students will perform the lab, collect data, and discuss, compare, and contrast their lab findings with the balanced chemical reaction equation. Students will present their structured inquiry investigations using a power-point presentation. Other groups along with the teacher will assess each group by using a provided rubric. Group assessments will be the deciding assessment for the final lab score. A follow up activity could investigate how NASA scientists launch real rockets into space and propose a procedure to investigate and collect data on a launching a heavier object at the school football field.
Answer:
The elements in the periodic table are arranged in order of increasing atomic number.
Explanation:
The outer electrons of an element are called the valence electrons. They help make an element stable.
Cesium : 1 valence electron<span>.
Magnesium : 2 valence electrons</span>
Answer:
Option b, The change in free energy of the reaction (ΔG)
Explanation:
Gibbs free energy is a measure of amount of usable energy in the system.
It is related with enthalpy (H), entropy (S) and temprature (T) as:
G = H - TS
The Gibbs free energy change (ΔG) provide spontaneity of a chemical reaction.
If ΔG is negative, then reaction is spontaneous that means reaction is moving towards forward direction.
If ΔG is positive, then reaction is non-spontaneous that means reaction is moving in backward direction.
If ΔG is zero, then reaction is at equilibrium.
Change in enthalpy only gives informtion about heat involed in a chemical reaction, it does not give information about direction of the reaction.
So, among the given options, option b is correct.
Answer:
Given : Diatomic molecule at 273K
'q' absorbed = positive = +100Cal = 100 x 4.184J = 418.4J
'W' done by system = negative = -209J
By first law of thermodynamics;
ΔU = q + W = 418.4 + (-209) = 209.4J
We know for diatomic molecule Cv=25R and CvΔT=ΔU
CvΔT=209.4
25RΔT=209.4
ΔT=5R209.4×2
And, Heat exchange=Cm×ΔT
where; Cm is molar heat capacity
Cm=ΔTHeat Exchange
substituting values for Heat Exchange = 418.4 and ΔT=5R209.4×2
Cm=5R
