Answer:
Metal cylinder: Work is <em>positive</em>
Foam: Heat is <em>positive</em>.
Explanation:
Work is done as a resultant force acts along a displacement. Heat is the flow of energy from one body to another, resulting in a either a rise or a drop in temperature of the bodies. Work and Heat are forms of energy and they can either be assigned a positive or negative sign with respect to a thermodynamic system.
If work is done on a body (thermodynamic system), the work is negative. On the other hand, if work is done by the body, it is termed as a positive work. Heat is positive when it flows into a thermodynamic system and negative when it is lost by the system.
In this case, though the metal cylinder is rolled up a ramp, the metal cylinder does a positive work along the displacement. Considering the foam, heat is gained by the foam (thermodynamic system) as it cools the environment, thus, heat is positive.
Answer:
D. 6.3 x 10-5 mol/L NaOH
Explanation:
Alizarin yellow is an indicator that is yellow when pH < 10.1. In the same way, thymol blue is blue when pH > 9
That means the pH of the solution is between 9 - 10.1
Any acid as HCl could have a pH of these.
The solution of 3.2x10⁻⁴M NaOH has a pH of:
pOH = -log[OH-] = 3.49
pH = 14-pOH = 10.51. The pH of the solution is not 10.5
Now, the solution of 6.3x10⁻⁵M NaOH has a pH:
pOH = -log[OH-] = 4.2
pH = 14-pOH = 9.8
The pH of the solution could be 9.8. Right option is:
<h3>D. 6.3 x 10-5 mol/L NaOH</h3>
Answer:
165 ml
Explanation:
We are given;
Initial volume; V_a = 55 ml
Initial molarity; M_a = 3 M
Molarity of desired solution; M_b = 0.75 M
Volume of desired solution; V_b = (55 + x) ml
Where x is the volume of water to be added.
To solve for V_b, we will use the equation ;
M_a•V_a = M_b•V_b
V_b = (M_a•V_a)/M_b
V_b = (3 × 55)/0.75
V_b = 220 mL
Thus;
(55 + x) = 220
x = 220 - 55
x = 165 mL
Answer:
0.99mol/L
Explanation:
Molarity ( M) = # of moles of solute / volume of solution (L)
Volume of Solution = 100 mL or 0.1 L
Molarity ( M) = # of moles of solute / volume of solution (L)
Molarity (M) = 0.099 mol / 0.1 L = 0.99mol/ L