Chem Final Lab

Apply the trends of oxidation state of chlorine? Asimple rule to remember is the oxidation state is for unmixed atoms the same as their charge.

-1

which of the elements is with lowest electronegrativity?

-Lithium -Francium -helium -neon Answer; Francium

what kind of experiment would help you categorize some of the elements?

-measure their electrical conductivity -test their ductility -observe their shininess ALL OF THE ABOVE! are correct

guess how many water molecules self-ionize in one liter of water

0.0000001 moles

the neutralization reaction of sulfuric acid and sodium hydroxide is below ___H2SO4+_____NaOH= ______Na2SO4+ ______H2O

1,2,1,2

how many electrons are in the atom Mg

12 electrons

How many neutrons does the nucleus of an aluminum have?

14

pH+pOH=

14

What is the total number of valence electrons in CO2

16

you identified potassium in the sample you bought back from Mars. How many protons does it have?

19 protons

B2H6+O2=HBO2+H2O after you balance the reaction above, what is the stoichiometry of B2H6:O2

1:3

How many electrons are shared between two Cl2 atoms

2

what results from a reaction of a base (BOH) and hydronium ion (H3O+)

2 H2O and B+

the final burette reading is 28.45mL and the initial burette reading is 5.60mL

22.85

B2H6+O2=HBO2+H2O after you balance the reaction above what is the stoichiometry between HBO2:H2O? write the form X:Y in the bank

2:2

What is the atomic number of lithium?

3 as the number of protons

What is atomic number of an atom that has 5 neutrons and 4 electrons

4 the atom should have as many protons as electrons

Which of the following represents a isotope for Lithium 7/3 Li

4/3 Li (the one with the same bottom number)

NH3(g)+NO(g)=N2(g)+H2O(g) balance the reaction and write what is the stoichiometry of NH3:NO? write the answer X:Y format

4:6

How many moles of lithium nitrate are theoretically produced if we start with 3.4 moles of Ca (NO3)2 and 2.4 moles of Li3PO4? Reaction: 3Ca(NO3)2+2Li3PO4=6LiNO3+Ca3(PO4)2

6.8

when we are reacting NaOH and H2SO4 for titration, what is the pH at the equivalence point?

7

based on what you know about their location in the periodic table, What do Cs and Cl react to

CsCl

Why didnt you just clean the spill of acid with water?

because acid reacts with water

why are melting point of ionic compounds higher than covalent compound?

because ions are tightly packed as a crystal lattice

in order for the gravimetric analysis to be valid we want all of the chloride ions to precipitate. How can we ensure this?

by letting the silver ions be in excess

what do you think is the reason for a decreasing atomic radius within one period?

increasing number of protons

the completion of acid-base titration is represented by the end point and equivalence. what is end-point? it is where the ----- changes color.

indicator

the second element identified has 26 protons but only 23 electrons. can you tell me the name of it after consulting the periodic table

it is a cation of ion

what is the atomic number of an anion that has 5 neutrons and 4 electrons?

less then 4- an anion should have less protons than electrons

Why is it dangerous to wear contact lenses in the lab

liquid can be trapped under them

if we talk about ions it simply means that an atom has gained of lost electrons by transfer from or to other atoms during the formation of an ionic bond. Lets recall! Whats the net charge of an anion?

negative

which of the element is clearly a non metal

neon

which symbol depicts oxidizing agent

(looks like a person with spikey hair)

Cl (chloride) is a part of the element family halogons, Which are also known as salt formers. How mant valence electrons does Na (sodium) have when forming an ionic bond with Cl? As you remember, valence electrons are the ones in the outmost shell. write the number in the blank

8

what is the first thing you have to do if there is a fire in the lab

Alert people

isotopes

Atoms with the same number of protons but different numbers of neutrons

There are usually two different types of fire extinguishers: CO2 based extinguisher and foam based extinguisher. Never use a CO2 based extinguisher on a person. Do you know the reason why?

CO2 is freezing cold

to which of the main classes does Mercury Hg belong to non metals?

False

whats up with the elements that are in the same group as krypton? they have the same number of protons (T/F)

False

what does the following symbol mean?

Health hazard

you mission is to get higher concentration of ethanol from 20% (v/v). what type of matter is ethanol 20% (v/v)?

Homogenous mixture

the first element you identified has 12 protons. Can you tell me the name of it after consulting the periodic table?

Mg

Which group of elements have a full octet of electrons? Write the popular name they are called. There are two words

Noble gas

What is point A called

Triple point

Ionic compounds typically have a higher melting point than covalent compunds

True

a standard solution is a solution of accurately known concentration. what is a standard solution for titration sulfuric acid in a acid-alkali titration? _______ such as sodium hydroxide.

alkali

what precautions should you take when working with strong acids and bases

always wear goggles and gloves

remember the brosted-lawry definition of acids and bases? whats is water according to this definition?

an acid and a base

what do you think is the reason for an increasing atomic radius within one group?

increasing number of electron shells

what makes an acid acidic?

chemical structure

which of the following is insoluble in water

copper wire

what type of compound is caffeine?

covalent

what is point b called

critical point

what should we do to reduce the risk when working with high concentrated acid and base?

dilute the acid

What are the different colors caused by that we can see in the flame test?

electrons falling back into their original shell

what do you have to do if there is an unexpected violent chemical reaction in the bottle

evacuate

The following equation is balanced CH4+2O2=CO2+H2O

false

safety eyewear is a type of personal protective equiptment that is rarely worn in the lab

false

the curve shows all three states of matter clearly

false

the intake of acidic or alkaline foods affects the blood pH

false

what is the main function of burette? diluting solution in precise volume

false

what do you think we need to do to help the lake ecosystem?

find out the acid concentration so we can neutralize it

you may notice that the slope in ice segment is steeper than the water segment.

greater heat is required to raise the temperature of water

Which unit used to express acidity of an acid or alkaline solution

pH

which of the elements you tested doesn't have a characteristic metallic appearance?

phosphorus

the heating curve

picture with a curve- it shows a continuous increase in temperature

Based on what you have seen, which is the best definition for an acid? acids donate ______ in aqueous solution

protons

what is the definition of a base? bases accept _______

protons

What are subatomic particles?

protons, neutrons, electrons

if you have glass of pure water,without any acids or bases, how many hydronium ions do you expect? The ______ number as OH-

same

the heating curve above

shows a continuous increase in temperature

besides ethonal and water, we see the heating curve of a metal. see the curves below. careful with the scale. which phase is the easiest to heat?

solid metal

which of the three chemicals are conductive in water

substance 2 and KCl

what do you have to do before leaving the lab, to make sure you don't carry traces of chemicals outside?

take off your lab coat them wash your hands

why the temperature remains constant during the phase changes

the heat is used to convert the states of matter

AgNO3+ HCl= AgCl+ HNO3 can you see the reaction stoichiometry how the number of moles of AgCl formed correlates to the number of moles of AgNO3 consumed

the number of moles are the same

which of the following is not a valid reason for the percentage yield of the reaction being below 100%

the product is not completely dry

what is the smallest pH possible

there is no fixed minimum

why does the correct Lewis structure CO2 involve a double bond between each of the oxygen atoms and carbon atoms

to complete the octet for carbon

why do we use a volumetric flask

to obtain accurate and precise volume

If a flammable substance is spilled, you should turn off or remove all sources of ignition in the area? (T/F)

true

carbon dioxide expands explosions this is not considered a chemical reaction?

true

compare the heating curve on the screen with the heating curve of water at normal pressure (1atm). you assume that the melting and boiling point will change with pressure

true

the temperature remains constant during the phase changes

true

when compounds containing polyatomic ions dissolve, the polyatomic ions usually dissolve as intact units.

true

when moving from left to right across the periodic table , ionization energy is increasing?

true

if we use bromothymol blue as an indicator, when will we reach the endpoint?

when the solution turn from yellow to blue

what's the difference in concentration of hydronium ions between pH 1 and pH 4

x1000

doe this image show toxic

yes

What should you Not do if a persons clothes suddenly catch fire?

you should not wrap a fire blanket around a standing person