Chemistry Basics and Scientific Method

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What is the name of the statement that sums up what you learned from an experiment and indicates if the hypothesis is proven or disproven?

control group

conclusion (correct)

procedure

hypothesis

What is a prediction or possible explanation to a question that can be tested in an experiment called?

graph

data

procedure

hypothesis (correct)

Which of the following represents the number 2.34x10^-7 in decimal notation?

23400000

23400

0.000000234 (correct)

234000

What is the correct expression of the number 0.051065 to four significant figures?

0.05106 Signup and view all the answers

Which set of measurements best represents good accuracy for a liquid volume of 20.5 mL?

20.2 mL, 20.5 mL, 20.3 mL, 20.1 mL Signup and view all the answers

What is the chemical formula of diphosphorus monobromide?

P2Br2 Signup and view all the answers

Which of the following is considered a chemical reaction?

bleaching your clothes Signup and view all the answers

Which one of the following is a chemical equation?

C + O2 → CO2 Signup and view all the answers

As you move from left to right across the periodic table, what happens to atomic radius?

atomic radius decreases Signup and view all the answers

Which gas most closely resembles ideal gas behavior?

Helium Signup and view all the answers

What is the balanced form of the equation: Ag + O2 → Ag2O?

Add a 2 in front of Ag and a 1 in front of Ag2O Signup and view all the answers

Which is NOT an acceptable name for Hg2Cl2?

mercury (II) chloride Signup and view all the answers

What occurs to the volume of a fully inflated balloon when it is taken outside on a cold day?

Its volume decreases Signup and view all the answers

Which of the following substances is NOT an acid?

milk Signup and view all the answers

What is the standard pressure of the atmosphere at sea level?

All of the choices Signup and view all the answers

In which flask is the pressure highest if each contains the same number of molecules?

Flask 2 Signup and view all the answers

When NH4Cl hydrolyzes, the resulting solution is what type?

acidic Signup and view all the answers

What is the molar mass of a gas if 1.60 grams occupies a volume of 2.24 L at STP?

16.0 g/mol Signup and view all the answers

Which two acids are mixed in aqua regia, a reagent used to dissolve gold?

hydrochloric and nitric acids Signup and view all the answers

Which conjugate acid/base pairs should be used for preparing a buffer near pH 7.15?

Sodium dihydrogen phosphate / sodium hydrogen phosphate (pKa2 = 7.20) Signup and view all the answers

When chromium changes from an oxidation state of +3 to +6, what must happen to Cr3+?

Lose 6 electrons Signup and view all the answers

During silver electroplating, what happens to silver ions in solution?

Are reduced at the cathode Signup and view all the answers

Which equation does NOT represent a redox reaction?

H2O + CO2 → H2CO3 Signup and view all the answers

What is the %w/w H2O in the cheese sample if its initial mass is 875.4 mg and the final mass is 545.8 mg?

31.45% Signup and view all the answers

What is the best procedure to ensure quantitative transfer of a precipitant from a beaker to filter paper?

Most of the liquid above the ppt is decanted first, bulk of the ppt is transferred through a stirring rod and the beaker is washed several times with small volumes of wash solution. Signup and view all the answers

Which method should NOT be used to preserve a water sample collected for analysis of oil and grease?

Collected in plastic bottle Signup and view all the answers

When oil and water come into contact, how will they behave?

Separate according to their densities Signup and view all the answers

What defines conductivity in relation to electric current?

The ability of a substance to conduct electric current, which is the reciprocal of resistivity Signup and view all the answers

What unique property does water have compared to other materials when in solid form?

Solid water (ice) is less dense than liquid water (ice floats in water) Signup and view all the answers

Which of the following statements about electrical conductivity is FALSE?

Increasing temperature has no effect on its value Signup and view all the answers

Which of the following statements about pH is FALSE?

Higher pH values indicate stronger acids Signup and view all the answers

What is the actual volume contained in a 50.0 mL volumetric flask given the mass of water is 50.1227 g and its density at 25 C is 0.99707 g/mL?

50.27 mL Signup and view all the answers

What conclusion can the lab supervisor draw after titrating NaOH with HCl, using 20.32 mL of acid at the endpoint?

The analysis is as accurate as can be expected using this apparatus. Signup and view all the answers

In which titrations does pH = 7.0 occur at the equivalence point?

Strong acid/strong base Signup and view all the answers

Which of the following practices is not recommended for good sampling?

Collecting the sample in a reactive container. Signup and view all the answers

In liquid-liquid extraction, if a drop of water added to the top layer dissolves, what does this imply about that layer?

It is aqueous. Signup and view all the answers

What is the process called when a sample is heated to its solvent's boiling point and volatile analytes are collected from the vapor phase?

Distillation Signup and view all the answers

Which type of analysis is not suitable for glass containers?