MDC CHM 1045L MIDTERM QUESTION BANK
A 2.25g sample of magnesium nitrate contains how many moles of this compound?
0.0152
How many ml of 12 M HCl are required to prepare 500 ml of 6M HCl?
250 ml
Elements in group 1A are known as
Alkali metals
A solution is a mixture:
In which a solid solute is always dissolved in a liquid solvent
If 2.0 ml of 6.0 M HCl is used to make a 500 ml aqueous solution, what is the molarity of the diluted solution?
0.024 M
What is a property of a base?
bitter taste
A neutralization can occur between an acid and a base
True
To 225 ml of 0.80 M solution of KI, a student adds enough water to make 1.0L of a more diluted KI solution. What is the molarity of the new solution?
0.18 M
What is the molarity of a solution containing 8.0 g of solute in 500 mL of solution? Note: formula mass of the solute is 24g
0.67 M
Which of the following are combustion reactions?
1) CH4(g) + O2(g) = CO2(g) + H2O 2) CaO(s) + CO2(g) = CaCO3 3) PbCO3(s) = PbO(s) + CO2(g) 4) CH3OH(l) + O2(g) = CO2(g) + H2O(l) Answer: both 1 & 4
How many moles or carbon dioxide are there in 52.06 g of carbon dioxide?
1.183
The specific gravity of sulfuric acid in a bottle is 1.3. The density of sulfuric acid will be:
1.3
How many molecules of CH4 are in 48.2 g of this compound?
1.81 x 10^24
How many mL of 3M HCl are needed to make 300 mL of 0.1 M of HCl?
10mL
What is the molarity of a solution containing 9.0 moles of solute in 500 mL of solution? Note: formula mass of the solute is 24g
18.0 M
When the equation: Al(NO3)3 + Na2S = Al2S3 + NaNO3 is balanced, the coefficients are
2, 3 , 1, 6
The density of silver is 10.5 g/cm^3. What would be the mass in grams of a piece of silver that occupies a volume of 23.6 cm^3?
248
If the precent (mass/volume) for a solute is 4% and the volume of the solution is 750 ml, what is the mass of solute in solution?
30 g
What is the mass % of carbon in C2H6SO?
30.7
What mass of sucrose, C12H22O11, is needed to make 500 ml of a 0.200 M solution?
34.2 g
What mass of Na2SO4 is needed to make 2.5 L of 2.0 M solution?
710g
Identify the piece of glassware that provides the least precise volume measurement of a liquid
A beaker
When an acid reacts with a base what compounds are formed?
A salt and water
Hydrates results from a process known as
Absorption of water
Most solids
Are dense and incompressible
One of the indicators of a chemical reaction is
Both a formation of gas and a change in color
Increasing the temperature of a solution will generally
Both increase the rate at which a solute dissolves and increase the amount of solute that dissolves
What measuring instrument is used in a titration?
Buret
Holding the temperature constant while adding more solute to a solution that already has solute crystal at the bottom of the container:
Cause more solute crystals to appear at the bottom of the container
Which of the following operations usually makes a substance dissolve faster in a solvent
Crushing the substance into a power Raising the temperature Agitation ALL OF THE ABOVE^
A common lab practice when handling chemicals, is to discard the excess back into the chemical bottle
False
A proper technique for volumetric analysis is to rinse the burette 3 times with the acid
False
If you wear contact lenses, it is recommended that you wear them during an experiment
False
In a chemical change that goes to completion, the reaction stops once the product is formed
False
Insoluble materials are to be discarded in the waste basket after the experiment
False
One equivalent of an acid is the mass of an acid that will donate 2 moles of hydrogen to a base
False
The process of determining the concentration of a solution is called molarity, determined by usage of equivalent amount of volumes
False
When filling a burette, the volume being added must be measured first then added
False
When metals react with other elements, like nonmetals, they enter into a combination in which they gain electrons
False
The temperature of an object can be described as
Heat contained in the object
A combination of sand, salt, and water is an example of a:
Heterogeneous mixture
Which one of the following is often easily separated into its components by simple techniques such as filtering or decanting?
Heterogeneous mixtures
In most measurements, the quality of an object is compared to
It's precision
What is the physical state in which matter has no specific shape but does have a specific volume?
Liquid
The density of an object that floats in water is
Lower than the density of water
What is obtained when phosphoric acid and magnesium hydroxide are mixed?
Magnesium phosphate and water
What are the products are the reaction of one mole of magnesium hydroxide and a mole of sulfuric acid?
MgSO4 + 2H2O
Of the reactions below, which one is a decomposition reaction?
NH4Cl → NH3 + HCl
What does not change when a solution is diluted by the addition of a solvent?
Number of miles of solute
The density of copper is about 8.96 g/ml. This means that a certain mass of copper will:
Occupy a volume that is 8.96 times smaller than the volume occupied by the same mass of water
In a normal reaction, the reactants continue to react with each other until
One of the reactants is completely consumed
In order to obtain accurate results during titration, we must
Perform a rough trial
One possible reason for obtaining a lower than expected yield during an experiment is
Side reaction
When predicting whether a reaction will or will not occur, one of the criteria used is:
Single displacement of a solid
Which of the following is the property of an acid?
Sour taste
Since gases usually have a much lower density, the unit volume is usually
The cm^3
When determining the concentration of an acid during titration, we must consider
The concentration of the base used to titrate
The maximum amount of product in a chemical reaction can be calculated by
The quantities of both reactants and products and their coefficients
164.0 g of a substance occupy a volume of 120.0ml. In relation to water, which statement is true?
The substance will sink in water
A piece of metal is heated, then submerged in cool water. Which statement described what happens?
The temperature of the water will increase, and the temperature of the metal will decrease
An independent variable is one such as
The variable that remains unchanged during the experiment
What is the purpose of a titration?
To determine the concentration of an acid or base
A reactant that is completely consumed is called limiting reagent
True
A suitable indicator will change colors when equivalent amounts of an acid and a base are present
True
Decanting a liquid that is mixed with an insoluble solid can be considered a separate technique
True
Formation of a solid is an indication of a reaction
True
Graphs are useful tools for organizing and displaying experimental data
True
In a chemical change that goes to completion, the quantity of product at that point is the maximum obtainable
True
In order to prepare a standard solution of an acid, a volumetric flask must be used
True
Many ionic compounds left open to the air will absorb water from the atmosphere and firm compounds known as hydrates
True
Normality is the concentration of a solution expressed in terms of the number of equivalents
True
Phenolphthalein is an indicator used to signal the end point of a titration
True
The accuracy of a measurement can be described by means of error and % error
True
The density of an object that floats is less than the density of the liquid in which it's found
True
The reliability of a measurement can be described in terms of its precision and accuracy
True
Volumes being calculated for the experiment can be accurately measured by using a beaker
True
The accuracy of a measurement can be described by
True value
Precision refers to
how close a measured number is to other measured numbers
Accuracy refers to
how close a measured number is to the true value