Answer: There are five signs of chemical change
- Color Change
- Production of an odor
- Change of Temperature
- Evolution of Gas (bubbles start to form)
- Precipitate (starts to form a solid)
When these signs start to form you know chemical change is at work.
Hope this helps :)
Answer:
The strongest force that exists between molecules of Ammonia is <em>Hydrogen Bonding</em>.
Explanation:
Hydrogen Bond Interactions are those interactions which are formed between a partial positive hydrogen atom bonded directly to most electronegative atoms (i.e. F, O and N) of one molecule interacts with the partial negative most electronegative atom of another molecule.
Hence, in ammonia the nitrogen atom being more electronegative element than Hydrogen will be having partial negative charge and making the hydrogen atom partial positive. Therefore, the attraction between these partials charges will be the main force of interaction between ammonia molecules.
Other than Hydrogen bonding interactions ammonia will also experience dipole-dipole attraction and London dispersion forces.
<span>While
treating food with gamma rays kills microorganism by damaging their DNA, the energy
of gamma rays rips off electrons from atoms hence ionizing them (causing free radicals).
However, gamma rays do not make the food atoms radioactive. The body has a natural
mechanism of riding the body of free radicals. However, large quantities of radicals in the body can cause
damage.</span>
Answer:
25.2°C
Explanation:
Given parameters:
Energy applied to the water = 1000J
Mass of water = 50g
Final temperature = 30°C
Unknown:
Initial temperature = ?
Solution:
To solve this problem, we use the expression below:
H = m c Ф
H is the energy absorbed
m is the mass
c is the specific heat capacity
Ф is the change in temperature
1000 = 50 x 4.184 x (30 - initial temperature )
1000 = 209.2(30 - initial temperature)
4.78 = 30 - initial temperature
4.78 - 30 = - initial temperature
Initial temperature = 25.2°C
A solution (in this experiment solution of NaNO₃) freezes at a lower temperature than does the pure solvent (deionized water). The higher the
solute concentration (sodium nitrate), freezing point depression of the solution will be greater.
Equation describing the change in freezing point:
ΔT = Kf · b · i.
ΔT - temperature change from pure solvent to solution.
Kf - the molal freezing point depression constant.
b - molality (moles of solute per kilogram of solvent).
i - Van’t Hoff Factor.
First measure freezing point of pure solvent (deionized water). Than make solutions of NaNO₃ with different molality and measure separately their freezing points. Use equation to calculate Kf.
