precise or accurate?
Explain the difference between accuracy and precision
Accuracy compares a measurement to an accepted or expected value. Precision refers to the exactness or repeatability of a measurement
Give the three equations for density, mass, and volume
OR
the one unified equation from which you can solve all others
d=m/v; m=d*v; v=m/d
OR
m/d*v
Plum Pudding Model
J.J. Thomson
Calculate the molar mass of carbon dioxide (CO₂)
44.01 g/mol
the rate at which an isotope decays is?
half-life
Which is more precise? 73.4 L or 734 mL
734 mL
a 50.0 mL sample of water from the dead sea has a density of 1.24 g/mL. Calculate the mass of the sample
62.0 g
m= d * V
m = 1.24g/mL * 50.0 mL
Crookes Tube
J.J. Thomson
A sample of carbon dioxide (CO₂) has a mass of 44 grams. Determine the number of moles of carbon dioxide in the sample.
1 mol
Complete the following equation modeling the decay of einsteinium. What type of decay is this?
25299Es --> AZX + 42He
25299Es --> 24897Bk + 42He
Alpha Decay
Draw a bullseye that is precise but not accurate
A bullseye that is precise but not accurate would mean that the shots consistently land in the same relative location but not necessarily in the correct or intended spot.
43.2 mL
V = m / d
V = 974 g / 22.56 g/mL
Gold foil experiment
Ernest Rutherford
Consider the reaction: 2H2+O2→2H2O. If you have 4 moles of oxygen (O₂), calculate the number of moles of water (H₂O) produced.
8
Complete the following equation modeling the decay of radium. What type of decay is this?
22586Ra --> AZX + 0-1e
22586Ra --> 22589Ac + 0-1e
Beta decay
Imagine you are conducting an experiment to determine the acceleration due to gravity. You perform a series of measurements using a highly sensitive apparatus and obtain the following results:
Trial 1: 9.82 m/s² Trial 2: 9.81 m/s² Trial 3: 9.80 m/s²
a. Explain whether these measurements are precise, accurate, both, or neither.
(accepted value of acceleration due to gravity is 9.81 m/s2)
The measurements are both precise and accurate. They are precise because they exhibit a small range of variation, and they are accurate because they are close to the true value of the acceleration due to gravity.
A metal cube has a mass of 75 grams and a volume of 125 cubic centimeters. Calculate the density of the metal.
0.60 g/cm3
d = m/v
d = 75g/125 cm3
Most commonly used model to date
Neils Bohr
Determine the molar mass of magnesium phosphate (Mg₃(PO₄)₂).
262.86 g/mol
Promethium-146 is a radioactive isotope that has a half-life of 5.5 years. How many years will it take for a 20.6 mg sample to decay to 1.3 mg?
22 years
4 half-lives
The engineer uses a highly accurate micrometer and records the following measurements for a specific component known to be 5.00 mm:
Measurement 1: 4.98 mm Measurement 2: 5.01 mm Measurement 3: 4.99 mm
a. Evaluate the precision and accuracy of these measurements, considering the desired specifications for the component's diameter.
These measurements are precise but not accurate as none of the measurements are to the exact specifications of the desired component measurement
A rectangular block has a density of 1.2 g/cm³ and a mass of 240 grams. Find the volume of the block.
200 cm3
v = m/d
v = 240 g/ 1.2 g/cm3
Current, most accurate model of the atom
Quantum-Mechanical Model
Calculate the molar mass of ammonium sulfate
ammonium = (NH4)+1
sulfate = (SO4)-2
132.14 g/mol
complete the following equation and identify if it represents fission or fusion.
23592U + 10n --> 9038Sr + AZX +210n
It is fission
23592U + 10n --> 9038Sr + 14454Xe +210n