Chemistry Lab Practical
What is the combined mass in grams of objects that have masses of 0.2000 kg, 80.0 g, and 524 mg?
0.2000kg * 1 g/0.001kg = 200 g 524 mg * 1g/ 1000 mg = 0.524 g 200g + 80.0 g + 0.524 g=280.524 g
A recipe calls for a bake temperature of 205 C. What temperature in F should be set on the oven?
1.8 (205) + 32 = 401 F
A pencil is 16.2 cm long. What is its length in millimeters?
16.2 cm x 10 = 162 mm
1 inch = ____ cm
2.54 cm
A beaker has a mass of 225.08 grams. When a liquid is added to the beaker, the combined mass is 238.254 g. What is the mass in grams of the liquid?
238.254 grams - 225.08 grams = 13.174 grams = 13.17 grams
What is an equality and how is it used to write a conversion factor?
An equality is an expression of quantity in 2 different units. When an equality is written as a fraction in the ratio is a conversion factor. Two fractions are always possible. EX: 1 km = 1000 m
A sugar-water mixture contains 45.8 g of sugar and 108.5 g of water. What is the percent by mass of sugar and percent by mass of water in the solution?
45.8 g + 108.5 g = 154.3 g 45.8 g/154.3 g = 0.2968 0.2968 x 100 = 29.7% water 108.5 g / 154.3 g = 0.7031 0.7031 x 100 = 70.3%
1 pound = ____ gram
454 g
How does a graph help us interpret scientific data?
By making a visual explanation that allows you to see a change in the data which you can use to predict a trend or track other noteworthy details.
Why would heating the gas in an air balloon make the balloon rise?
Hot-air balloons float because the air trapped inside the balloon is heated up by a burner, making it less dense than the air outside. When the gas (air) in a hot air balloon is heated it becomes less dense. This makes the balloon more buoyant so it rises. Because heating the air inside the balloon makes it less dense than the air surrounding the outside of the balloon, so it will rise.
Is a body temperature of 39.4 C a normal temperature or does it indicate a fever?
If temperature is over 37.8 C or 100 F it is considered a fever.
What are the rules for rounding off numbers?
If the first number to be dropped is less than 5, it and all the following numbers are dropped. If the first number to be dropped is 5 or greater, the numbers are dropped and the last retained number is increased by 1.
A patient received 825 mL of fluid in one day. What is that volume in liters?
825 mL / 1000 = 0.825 L
1 qt = ____ mL
946 mL
How could two students obtain different values for the calculated areas of the same rectangle?
human error/different measuring tools
Volume of Rectangular Solid Formula
length x width x height = volume
How is the number of digits determined for an answer obtained by adding or subtracting?
the number of significant figures is determined by the measured number with the fewest decimals.
How do you determine how many significant figures to keep in an answer obtained by multiplying or dividing?
your answer should be equal to the amount of significant figures as your least precise measurement.
How to determine the number of valence electrons based on group number
the group number determines the number of valence electrons the element contains, Helium has 2 not 8.
Hazard Rating
1 - little hazard 4 - extreme hazard Health Hazard - likelihood that a material will cause injury due to exposure by contact, inhalation, or ingestion. Flammability Hazard - potential for burning Reactivity Hazard - instability of the material by itself or with water with subsequent release or energy. Special Hazards - reactivity with water or OX for oxidizing properties
How many liters of plasma are present in 8.5 pints? (1 qt = 2 pt)
1 Pint = 0.473176 Liters 4.022 liters
1 kg = _____ g
1000 g
1 L = _____ mL
1000 mL
A roll of tape is 45.5 inches. What is the length of the tape in meters?
45.5 in x 2.54/1 in = 115.6 115.6 cm / 100 = 1.156 = 1 m
An infant has a mass of 3.40 kg. What is the weight of the infant in pounds?
3.40 kg/1 x 1000 g/1 kg x 1lb/454 g = 7.489 lbs
Specific Heat for Water
4.184
energy level of each ___-block is one less than its period number
D
An object made of aluminum has a mass of 8.37 g. When it was placed in a graduated cylinder containing 20.0 mL of water, the water level rose to 23.1 mL. Calculate the density and specific gravity of the object.
D = m/v 8.37/3.1 = 2.7 g/mL 2.7 / 1g/mL = 2.7 specific gravity
Density Formula
D=mass/volume
Waste Disposal
Disposal symbol indicates that items that may have come in contact with body fluids should be placed in your lab's designated container. Liquid wastes should not be poured down the drain into the sewage system. Biohazard symbol indicates procedures that may pose health concerns. Caution symbol points out instruments, substances, and procedures that require special attention to safety. Metals should be placed in a container to be recycled. Nonhazardous chemical waste that are soluble in water and are not hazardous may be emptied into the sink. Hazardous chemical wastes it must be placed in a container that is labeled for waste disposal and label if hazardous, name of chemical waste, date the container was placed in lab.
Difference between group number and period number.
Each column is called a group. The elements in each group have the same number of electrons in the outer orbital. All of the elements in a period have the same number of atomic orbitals. For example, every element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons.
energy level of each ___-block is two less than the corresponding period number.
F
What is the difference in specific gravity & density?
Ratios of each other Density is the measure of the amount of mass per volume. density = mass / volume Specific gravity is a measure of density relative to the density of a reference substance.
Formula for Specific Gravity
Specific Gravity = density of liquid (g/mL)/density of water (1.00g/mL)
Specific Gravity Formula
Specific Gravity = density of liquid/density of water
Specific Heat Formula
Specific heat = Heat/(Mass x change in temperature)
Celsius to Fahrenheit
Tc = (Tf - 32) / 1.8
Fahrenheit to Celsius
Tf = 1.8 (Tc) + 32
Why do elements release different colors when burned? What does this have to do with electron configurations and energy levels?
The Bohr model says that electrons exist only at certain allowed energy levels. When you heat an atom, some of its electrons are "excited* to higher energy levels. When an electron drops from one level to a lower energy level, it emits a quantum of energy.The wavelength (color) of the light depends on the difference in the two energy levels. We can see only those transitions that correspond to a visible wavelength.
Celsius to Kelvin
Tk = Tc + 273
True/False: heat gained by water is equal to heat lost by the substance that heated the water.
True
True/False: mass of what burned away is the mass that you use to calculate specific heat.
True
Specific Heat of a Metal Formula
cal/(mass of metal (g) X change in temperature (C))
Personal Protective Equipment
hair tied, closed toe shoes, goggles, protective clothing, no food or drink
Percent by Mass (component 1)
mass (g) of component 1/mass (g) of the mixture TIMES 100 = % of component 1
Percent by Mass (component 2)
mass (g) of component 2/mass (g) of the mixture TIMES 100 = % of component 2
Density of Liquid Formula
mass (g) of liquid/volume (mL) of liquid
Density of Substance Formula
mass of substance (g)/volume of substance (mL)
Volume of Cube Formula
v = L^3
Volume of Cylinder Solid Formula
volume = (3.14D^2H)/4
Chemical Handling
wash hands immediately if contaminated, keep chemicals away from direct heat/sunlight, check label twice, small amounts of chemical, do not return chemicals to the original containers, do not waste chemicals, smell cautiously, do not shake lab thermometers, heat only heat-resistant glassware, never heat a closed container,
What property of oil makes it float on water?
water is denser than oil - more water mass than oil per unit volume