Chem Lab test
A pair of students found the temperature of 100. g of water to be 25.80°C. They then dissolved 7.63 g of AgNO3 in the water. When the salt had dissolved, the temperature of the water was 23.38°C. (a) Calculate ΔT for the water. (b) The dissolution was exothermic or endothermic? (c) The water gave up/absorbed energy to/from the dissolution process. (d) Based on this observation alone, the entropy must have decreased/increased
(a) -2.42 C (b) endothermic (c) gave up energy to the dissolution process (d) increased
Lewis structure for SO3 What is the bond angle? Hybridization? molecular shape?
- 120 -sp^2 -trigonal planar
Volume of a sphere?
(4/3) x pi x radius^3
What is the density of water with a mass of 18.29 grams and a volume of 18.1.
1.01 g/ml
Write the dissolution reaction of Al(NO3)3
Al(NO3)3 (s) → Al3^+ (aq) + 3NO3^-(aq)
Write the Net Bronstead acid base reaction of bleach (sodium hypochlorite, NaOCl) in water
OCl- + H2O → HClO^ + OH^-
Bases produce H3O^+ or OH^-
OH^-
acids are proton donors or acceptors?
donors
[Cu(H2O)4]2+(blue) + 4 Br− equilibrium reaction arrow [CuBr4]2−(yellow) + 4 H2O Adding KBr would cause it to turn... Cooling the exothermic reaction would cause it to turn...
yellow, yellow
If any of corrosive chemicals get in your eyes or on your skin, what is the proper response? What is the step that should be done?
-immediately flush the affected area -your lab partner should notify the TA immediately
Atomic Radii in Ångström (1 ✕ 10−10 m) Ne= .70 What is the volume of on atom of Ne
1.4 angstroms
how to find the hydronium ion concentration
10^-pH
What is the stoichiometry of HC2H3O2 to Ca(OH)2?
2:1
Write the precipitation between Al(NO3)3 and Na2CO3 List the spectator ions
2Al3^+ (aq) + 3CO3^2-(aq) → Al2(CO3)3 (s) NO3 and Na
Write the net precipitation reaction that occurs when a solution containing Fe3+ and Ba2+ is made basic (contains OH−) from the addition of NH3. (Use the lowest possible coefficients. Include states-of-matter under the given conditions in your answer.)
3OH1- (aq) + Fe3+ (aq) → Fe(OH)3 (s)
Equilibria can be treated mathematically with the equilibrium constant, K. For the reaction Fe3+ + SCN − equilibrium reaction arrow FeSCN2+, the equilibrium constant expression is [FeSCN2+ ] K = [Fe3+ ] · [SCN − ] At some temperature, a chemist found the following equilibrium concentrations. [Fe3+ ] = 8.27 ✕ 10−3 M, [SCN − ] = 8.53 ✕ 10−3 M, [FeSCN2+ ] = 6.28 ✕ 10−2 M What is the value of K?
890
If HCl were added to a solution containing lead(II) ions, sodium ions, nickel(II) ions, and potassium ions, which ions would precipitate? (Select all that apply.) A. lead ions B. nickel ions C. potassium ions D. sodium ions E. none of them
A
In the lab, a student must wear safety glasses or goggles... A. At all times B. unless they bother him/her C. Unless he/she has standard eyeglasses D. only when he/she is performing experiments E. unless he/she has contact lenses
A
When working with a Bunsen burner, which of the following precautions must be observed? (Select all that apply.) A. The area above the burner must be clear before it is lit. B. The burner must never be used in the presence of oxygen. C. The burner must never be left unattended. D. The burner must never be used to heat metal. E. If the flame blows out, the gas must be turned off, because gas could accumulate and an explosion could occur. F. Flammable liquids should never be heated with a Bunsen burner. G. The substance being heated should never be pointed at people. H. The area near the burner should be clear of paper and other flammables.
A, C, E, F, G, H
Proper lab equipment includes which of the following? (select all that apply) A. flowing robes B. a shirt that covers the shoulders and extends about 6" below the waist C. crop tops and hip hugger jeans D. a shirt with long, loose sleeves E. a shirt and pants that overlap about 6" in the middle to cover the torso F. sandals G. pants that extend to the ankles H.shorts I. shoes that cover the heels and toes J. tank tops
B, E, G, H
If a sodium hydroxide solution were added to a solution containing lead(II) ions, sodium ions, nickel(II) ions, and potassium ions, which ion(s) would remain in the supernatant? (select all that apply) A. lead ions B. nickel ions C. potassium ions D. sodium ions E. none of them
C and D
Write the net precipitation reaction that occurs when HCl is added to an aqueous solution containing Fe3+, Ba2+, and Ag+ ions. (Use the lowest possible coefficients. Include states-of-matter under the given conditions in your answer.)
Cl1- (aq) + Ag+ (aq) → AgCl (s)
Write the precipitation between Cr(ClO4)3 and Li3PO4 List the spectator ions
Cr3^+ (aq) + PO36-4(aq) → CrPO4 (s) ClO4 and Li3
The orange in fireworks is often due to the emission of light from Ca2+. If the primary wavelength is 668 nm, what are the frequency and energy of the light? (Enter your answers in scientific notation.)
Frequency= 4.49e+14 Energy= 2.98e-19
Acids produce H3O^+ or OH^-
H3O^+
Write the Net Bronstead acid base reaction of vinegar (acetic acid, HC2H3O2) in water.
HC2H3O2 + H2O → C2H3O2^- + H3O^+
How do you fine density of a substance?
Mass/volume
How do you find molecule from moles?
Moles x 6.022x10^23
Write the dissolution reaction of Na2CO3
Na2CO3 (s) → 2Na^+ (aq) + CO3^2- (aq)
lewis structure for N2O
The first image
bases are proton donors or acceptors?
acceptors
Strong acids (partially/completely) dissociate to form H+ ions
completely
How do you find mass %
mass of acetic acid in sample/ mass of vinegar solution titrated
What are pH probes used for?
measurement of pH
how do you find molarity of a solution?
mmol acetic acid in sample/ ml of sample
What type of acids and bases are allowed to be rinsed down the drain?
normal non-toxic acids and bases
weak acids (partially.completely) dissociate to form H+ ions
partially
What is a bunsen burner used for?
produces a single open gas flame, which is used for heating, sterilization, and combustion.
HC14H14SO3(red) + H2O equilibrium reaction arrow C14H14SO3−(yellow) + H3O+ What color is the indicator in an acidic solution? (Acidic solutions are prepared by adding H3O+ ion.) Heating the exothermic reaction would cause it to turn
red, red
The body centered
simple cubic with a center atom
is HCl a strong or weak acid?
strong acid
What is an analytical balance used for?
used for the accurate weighing of samples and precipitates.
What is a centrifuge used for?
used for the separation of fluids, gas or liquid, based on density.
What is a buret used for?
used in quantitative chemical analysis to measure the volume of a liquid or a gas.
What is titration used for?
used to determine the unknown concentration of an identified analyte
What is a graduated cylinder used for?
used to measure the volume of a liquid.
is HC2H3O2 a strong or weak acid?
weak
