Stars on the main sequence fuse hydrogen into helium via a six-stage sequence of reactions
Answer:
The density is 5 g/cm3
Explanation:
The density (δ) is the ratio between the mass and the volume of a compound:
δ=m/v= 10 g/2 cm3= 5 g/cm3
Answer:
Because time is independent of distance, and distance is dependent of time.
Explanation:
Usually, on any graph, the independent variable is plotted on the x-axis and the dependent variable is plotted on the y-axis. Because of this, time, which is independent (time happens regardless of any other factor), is on the x-axis while distance, which is the dependent variable (can only take place in time), is on the y-axis.
The false positive from the response of hydrogen peroxide and the immunizing circle would be created by poor specificity. The recipe for specificity is TN/TN+FP. False-positive outcomes can be ascribed to meddling substances in nature where the strips are put away or utilized, for example, hydrogen peroxide (H2O2) or fade (hypochlorite).
2.0 L
The key to any dilution calculation is the dilution factor
The dilution factor essentially tells you how concentrated the stock solution was compared with the diluted solution.
In your case, the dilution must take you from a concentrated hydrochloric acid solution of 18.5 M to a diluted solution of 1.5 M, so the dilution factor must be equal to
DF=18.5M1.5M=12.333
So, in order to decrease the concentration of the stock solution by a factor of 12.333, you must increase its volume by a factor of 12.333by adding water.
The volume of the stock solution needed for this dilution will be
DF=VdilutedVstock⇒Vstock=VdilutedDF
Plug in your values to find
Vstock=25.0 L12.333=2.0 L−−−−−
The answer is rounded to two sig figs, the number of significant figures you have for the concentration od the diluted solution.
So, to make 25.0 L of 1.5 M hydrochloric acid solution, take 2.0 L of 18.5 M hydrochloric acid solution and dilute it to a final volume of 25.0 L.
IMPORTANT NOTE! Do not forget that you must always add concentrated acid to water and not the other way around!
In this case, you're working with very concentrated hydrochloric acid, so it would be best to keep the stock solution and the water needed for the dilution in an ice bath before the dilution.
Also, it would be best to perform the dilution in several steps using smaller doses of stock solution. Don't forget to stir as you're adding the acid!
So, to dilute your solution, take several steps to add the concentrated acid solution to enough water to ensure that the final is as close to 25.0 L as possible. If you're still a couple of milliliters short of the target volume, finish the dilution by adding water.
Always remember
Water to concentrated acid →.NO!
Concentrated acid to water →.YES!
