Answer:
1. Density can be used to identify a substance
2. Density can be used to ascertain whether a substance will float in water.
Explanation:
The calculation of the density of a substance can be used to identify the substance. If the density of a substance is calculated accurately, and compared with a table of standard densities, then we can identify that substance.
Also, density determines whether an object will float or sink in water. If an object is less dense than water then it will float in water. If it is denser than water, then it will sink in water.
The car's velocity after 5s : 10 m/s
<h3>Further explanation</h3>
Given
velocity=v=72 km/h=20 m/s
time=t = 5 s
acceleration=a = -2 m/s²
Required
velocity after 5s
Solution
Straight motion changes with constant acceleration
vf=final velocity
vi = initial velocity
Input the value :
The car is decelerating (acceleration is negative) so that its speed decreases
Answer:
6.142 moles of NaCl
Explanation:
We'll begin by writing the balanced equation for the reaction. This is given below:
2AlCl3 + 3Na2S —> Al2S3 + 6NaCl
Next, we determine the number of mole in 239.7 g of Na2S. This is illustrated below:
Mass mass of Na2S = 78.048g/mol
Mass of Na2S = 239.7g
Number of mole Na2S =..?
Mole = Mass /Molar Mass
Number of mole Na2S = 239.7/78.048 = 3.071 moles
Finally, we can obtain the number of mole of NaCl produced from the reaction as follow:
From the balanced equation above,
3 moles of Na2S reacted to produce 6 moles of NaCl.
Therefore, 3.071 moles of Na2S will react to produce = (3.071 x 6)/3 = 6.142 moles of NaCl
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Project: Modeling potential and kinetic energy
Assignment Summary
For this assignment, you will develop a model that shows a roller coaster cart in four different positions on a track. You will then use this model to discuss the changes in potential and kinetic energy of the cart as it moves along the track.
Background Information
The two most common forms of energy are potential energy and kinetic energy. Potential energy is the stored energy an object has due to its position. Kinetic energy is the energy an object has due to its motion. An object’s kinetic energy changes with its motion, while its potential energy changes with its position, but the total energy stays the same. If potential energy increases, then kinetic energy decreases. If potential energy decreases, then kinetic energy increases.
Potential energy related to the height of an object is called gravitational potential energy. Gravitational potential energy is directly related to an object’s mass, the acceleration due to gravity, and an object’s height.
Materials
One poster board per student Drawing utensils
Assignment Instructions
Step 1: Prepare for the project.
a) Read the entire Student Guide before you begin this project.
b) If anything is unclear, be sure to ask your teacher for assistance before you begin.
c) Gather the materials you will need to complete this project.
Step 2: Create your poster.
a) On the poster board, draw a roller coaster track that starts with one large hill, then is followed by a valley and another, smaller hill.
b) Draw a cart in four positions on the track as outlined below.
i. Draw the first cart at the top of the first hill. Label it A.
ii. Draw the second cart going down the first hill into the valley. Label it B.
iii. Draw the third cart at the bottom of the valley. Assume that the height of the cart in this position is zero. Label it C.
iv. Draw the last cart at the top of the second, smaller hill. Label it D.
c) Make sure that your name is on the poster. Step 3: Type one to two paragraphs that describe the energy of the cart.
a) Type one to two paragraphs describing the changes in potential and kinetic energy of the cart. Be sure to discuss how the potential and kinetic energy of the cart changes at each of the four positions along the track, and explain why these changes occur.
b) Make sure your name is on the document.
c) Later, you will submit this document through the virtual classroom.
Step 4: Evaluate your project using this checklist.
If you can check each criterion below, you are ready to submit your project.
Did you draw a model of a roller coaster track with one large hill, a valley, and a smaller hill?
Did you draw a cart on the track in the four required positions A–D? Did you label the cart at each of the four positions?
Did you type a paragraph describing the changes in potential and kinetic energy of the cart at each of the four positions on the roller coaster track? Did you explain why the changes in potential and kinetic energy occur?
Step 5: Revise and submit your project.
a) If you were unable to check off all of the requirements on the checklist, go back and make sure that your project is complete.
b) When you have completed your project, submit your poster to your teacher for grading. Be sure that your name is on it.
c) Submit the typewritten document through the virtual classroom. Be sure that your name is on it.
Step 6: Clean up your work space.
a) Clean up your work space. Return any reusable materials to your teacher and throw away any trash.
b) Congratulations! You have completed your project.
Electric energy and sink
Answer:
Explanation:
Question 7.
We can use the Combined Gas Laws to solve this question.
a) Data
p₁ = 1.88 atm; p₂ = 2.50 atm
V₁ = 285 mL; V₂ = 435 mL
T₁ = 355 K; T₂ = ?
b) Calculation
Question 8. I
We can use the Ideal Gas Law to solve this question.
pV = nRT
n = m/M
pV = (m/M)RT = mRT/M
a) Data:
p = 4.58 atm
V = 13.0 L
R = 0.082 06 L·atm·K⁻¹mol⁻¹
T = 385 K
M = 46.01 g/mol
(b) Calculation
