What is the total number of moles of solute in 250 milliliters of a 1.0 M solution of NaCl
Answers
First, the Molarity equation is M = mol/L. However, the problem is looking for the TOTAL NUMBER OF MOLES in which will have you to reposition the said equation: mol = M/L. Observe that you need L not mL, so you need to convert 250 mL to L that will results to .25 L. Then, substitute the value of the units to the formula and you should be able to get 4 moles.
Answer:
0.25
Explanation:
If there is no net force on an object, then the object will a) continue to accelerate B) begin moving slow down c) maintain it's rate of speed d) have to be at rest
Answers
If there is no net force on an object, then the object will maintain it's rate of speed. Basically, net force is the change in an object's motion. If it is stationary and not moving, the object will stay stationary. If the object is moving at a rate of 2 miles per hour, it will constantly continue to move 2 mph because there is no net force.
How much of a 5.0 g sample of strontium-90 will remain after 87 years?
Answers
Since radioacitive decay fallows first order kinetics you can use the equation lnA(t)=-kt+lnA₀. A₀=the initial amount of sample A(t)=the amount of sample after t years t=time k=rate constant
First you need to solve for the rate constant (k) to get the equation -((lnA(t)-lnA(0))/t=k which can simplify into k=-ln(A(t)/A₀)/t which can then be simplified further to ln(A₀/A(t))/t=k. I think the half life of strontium-90 is 28.8 years which means that when t=28.8 years, A(t) is going to equal 1/2 of A₀ and you can make the equation k=ln2/28.8 to get k=0.02408.
Now you need to solve for A(t) in the equation ln(A(t))=-kt+lnA₀ to get A(t)=e^(-kt+lnA₀) which simplifies to A(t)=A₀e^-kt. When you plug t=87, A₀=5g, and k=0.02408 into that equation you should get 0.616g.
Therefore after 87 years you will have 0.616g of strontium-90 if you started with a 5g sample.
I hope this helps. Let me know in the comments if anything is unclear.
chlorine has 7 outer energy level electrons and argon has 8. what is the difference in the reactivity of these two elements?
Answers
chlorine is more reactive than argon, because argon is not reactive at all. Chlorine only has to gain 1 valence electron
Chlorine is highly reactive as it seeks to gain an extra electron to balance its outer shell (max 8) and argon is stable because it has a stable outer shell
The sense of touch is produced by______ within the skin. dermis,muscles,neurons,feelings