The ML of 0.85 m NaOH required to titrate 25 ml of 0.72m hbr to the equivalence point is calculated as follows
calculate the moles of HBr used
moles = molarity x volume
25 x0.072/1000= 0.0018 moles
write the equation for reaction
NaOH + HBr = NaBr + H2O
from reacting equation the mole ratio between NaOH to HBr is 1:1 therefore the moles of NaOH = 0.0018 moles
volume = moles/molarity
0.0018/0.085 = 0.021 L in Ml = 0.021 x1000=21.18 Ml ofNaOH
Weathering would be chemical because it's more natural than physical
Scientists make hypothesis in order to make an educated guess on the outcome of the experiment.
<u>Answer:</u> The correct answer is Option D.
<u>Explanation:</u>
Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as 
The equation used to calculate enthalpy change is of a reaction is:
![\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f_{(product)}]-\sum [n\times \Delta H^o_f_{(reactant)}]](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5Csum%20%5Bn%5Ctimes%20%5CDelta%20H%5Eo_f_%7B%28product%29%7D%5D-%5Csum%20%5Bn%5Ctimes%20%5CDelta%20H%5Eo_f_%7B%28reactant%29%7D%5D)
Hence, the correct answer is Option D.
Answer:
2-4 minutes
Explanation:
Fastest changing temperature means larger change in temperature when subtracting final temperature from initial temperature in a given time period (given time period is 2 minutes for all the options)
For 0-2 minutes, our final temperature was 40 (at 2 min) and initial temperature was 20 (at 0 min), thus temperature change was only 20 C.
For 2-4, our final temperature was 80 (at 4 min) and initial temperature was 40 (at 2 min) thus temperature change was 40 C.
For 4-6, our final temperature was 100 (at 6 min) and initial temperature was 80 (at 4 min) thus temperature change was 20 C.
We are not given temperature at 8 min so option D is invalid.
As we can clearly see that in a given 2 minute period, option B has the fastest change because it changed 40C when compared to other options that changed only 20C from starting temperature.
Hope that makes sense.
