1.
PREPARE A 1%, 200mL SOLUTION OF BLEACH, HOW MUCH OF THE BLEACH CONCENTRATE IS NEEDED?
Correct Answer
A. 2mL
Explanation
THIS IS A DILUTION QUESTION, WHERE WE WERE NOT GIVEN AN INITIAL CONCENTATION. THEREFORE, WE WOULD USE THE EQUATION
a/ (a+b) x total volume.
typically we are mixing two fluids lets say a and b to make a total solution (a+b)
a is the volume or number of parts a
b is the volume or number of parts b
a+b represents the total solution
for percent solutions
a % means "a parts out of 100 total parts"
a+b which represents total parts =100 (the question does not have to give us b)
a/(a+b) = a/100
a/(a+b) x total volume for percent I= a/100 x total volume.
a/100 = 1/100, total volume is 200mL.
the volume of bleach concentrate needed is 1/100 x 200mL
1 divide by 100 = 0.01
0.01 multiplied by 200 = 2mL
2.
HOW MUCH BLEACH IS NEEDED TO MAKE A 6%, 50mL BLEACH SOLUTION
Correct Answer
A. 3mL
Explanation
THIS IS A DILUTION QUESTION, WHERE WE WERE NOT GIVEN AN INITIAL CONCENTATION. THEREFORE, WE WOULD USE THE EQUATION
a/ (a+b) x total volume.
typically we are mixing two fluids lets say a and b to make a total solution (a+b)
a is the volume or number of parts a
b is the volume or number of parts b
a+b represents the total solution
for percent solutions
a % means "a parts out of 100 total parts"
a+b which represents total parts =100 (the question does not have to give us b)
a/(a+b) = a/100
a/(a+b) x total volume for percent I= a/100 x total volume.
a/100 = 6/100,
total volume is 50mL.
the volume of bleach concentrate needed is
6/100 x 50mL
6 divided by 100 =0.06
0.06 x 50mL = 3mL
3.
HOW MUCH BLEACH IS NEEDED TO MAKE A 50mL BLEACH SOLUTION WITH ONE PART BLEACH AND 9 PARTS WATER
Correct Answer
A. 5mL
Explanation
THIS IS A DILUTION QUESTION, WHERE WE WERE NOT GIVEN AN INITIAL CONCENTATION. THEREFORE, WE WOULD USE THE EQUATION
a/ (a+b) x total volume.
lets say
a(substance of interest) is bleach and b is water
a = 1, b = 9, a+b = 10.
(we used "a" to represent bleach and not water because bleach is our substance of interest)
(we know that bleach is our substance of interest because we are making a bleach solution and not a water solution - the question told us that)
a = 1, b = 9, a+b = 10.
a/(a+b) = 1/(1+9) = 1/10
total volume is 50mL.
the volume of bleach concentrate needed is (1/10) x 50mL
1 divided by 10 =0.1
0.1 x 50mL = 5mL
4.
HOW MUCH BLEACH IS NEEDED TO MAKE A 1000mL BLEACH SOLUTION WITH 2 PARTS BLEACH AND 3 PARTS WATER
Correct Answer
C. 400mL
Explanation
THIS IS A DILUTION QUESTION, WHERE WE WERE NOT GIVEN AN INITIAL CONCENTATION. THEREFORE, WE WOULD USE THE EQUATION
a/ (a+b) x total volume.
lets say
a(substance of interest) is bleach and b is water
a = 2, b = 3, a+b = 5.
(we used "a" to represent bleach and not water because bleach is our substance of interest)
(we know that bleach is our substance of interest because we are making a bleach solution and not a water solution - the question told us that)
a/(a+b) = 2/(2+3) = 2/5
total volume is 1000mL.
the volume of bleach concentrate needed is (2/5) x 1000mL
2 divided by 5 =0.4
0.4 x 1000mL = 400mL
5.
HOW MUCH BLEACH IS NEEDED TO MAKE A 800mL, 1 to 20 dilution of BLEACH SOLUTION
Correct Answer
C. 40mL
Explanation
THIS IS A DILUTION QUESTION, WHERE WE WERE NOT GIVEN AN INITIAL CONCENTATION. THEREFORE, WE WOULD USE THE EQUATION
lets say
a(substance of interest) is bleach and b is water
a = 1, a+b = 20
(we used "a" to represent bleach and not water because bleach is our substance of interest)
(we know that bleach is our substance of interest because we are making a bleach solution and not a water solution - the question told us that)
ratios are written as "part to total"
this means ratio (a to total)
which is the same as ratio "a : total", where total =a +b
which means ratio a:a+b
ratio a:a+b can be rewritten as a/(a+b)
volume required = a/ (a+b) x total volume.
a/(a+b) = 2/(2+3) = 2/5
total volume is 1000mL.
the volume of bleach concentrate needed is (2/5) x 1000mL
2 divided by 5 =0.4
0.4 x 1000mL = 400mL
6.
HOW MUCH BLEACH IS NEEDED TO MAKE A 250mL, 1 :10 dilution of BLEACH SOLUTION
Correct Answer
B. 25mL
Explanation
THIS IS A DILUTION QUESTION, WHERE WE WERE NOT GIVEN AN INITIAL CONCENTATION. THEREFORE, WE WOULD USE THE EQUATION
dilution type is ratio (part:total) =(parts out of total) = (1 part bleach out of 10 parts total)
lets say
a(substance of interest) is bleach and b is water
a = 1, a+b = 10
(we used "a" to represent bleach and not water because bleach is our substance of interest)
(we know that bleach is our substance of interest because we are making a bleach solution and not a water solution - the question told us that)
ratios are written as "part : total"
this means ratio (a : total)
ratio "a:total" can be rewritten as "a parts / total parts"
volume required = a parts/ (total parts) x total volume.
a/(total) = 1/(10)
total volume is 250mL.
the volume of bleach concentrate needed is (1/10) x 250mL
1 divided by 10 = 0.10
0.10 x 250mL = 25mL
7.
HOW MUCH BLEACH IS NEEDED TO MAKE A 40mL, 1 :5 dilution of BLEACH SOLUTION
Correct Answer
A. 8mL
Explanation
THIS IS A DILUTION QUESTION, WHERE WE WERE NOT GIVEN AN INITIAL CONCENTATION. THEREFORE, WE WOULD USE THE EQUATION
dilution type is ratio (part:total) =(parts out of total) = (1 part bleach out of 5 parts total)
lets say
a(substance of interest) is bleach and b is water
a = 1, a+b = 5
(we used "a" to represent bleach and not water because bleach is our substance of interest)
(we know that bleach is our substance of interest because we are making a bleach solution and not a water solution - the question told us that)
ratios are written as "part : total"
this means ratio (a : total)
ratio "a:total" can be rewritten as "a parts / total parts"
volume required = a parts/ (total parts) x total volume.
a/(total) = 1/(5)
total volume is 40mL.
the volume of bleach concentrate needed is (1/5) x 40mL
1 divided by 5= 0.20
0.20 x 40mL = 8mL
8.
HOW MUCH OF A 70% ALCOHOL SOLUTION IS USED TO PREPARE A 4000mL, 5% ALCOHOL SOLUTION
Correct Answer
C. 285.7
Explanation
AN INITIAL CONCENTRATION HAS BEEN GIVEN, THEREFORE THE EQUATION TO BE USED IS
C1 X V1 = C2 X V2
FROM THE ABOVE EQUATION,
V1 = (C2 X V2)/C1
THE #1 REPRESENTS CONCENTRATE SIDE OF THE EQUATION (WHAT WE HAVE)
THE #2 REPRESENTS DILUTED SIDE OF TEH EQUATION (WHAT WE WANT TO MAKE)
C1 = THE CONCENTRATION OF THE CONCENTRATE
V1 = THE VOLUME (L, GALLONS, mL, uL, dL) OF THE CONCENTRATE NEEDED TO MAKE OUR DILUTION (FOR EXAMPLE TWO CUPS OR GALLONS OR mL, OR TEASPOONS OF FROZEN CONCENTRATED LEMONADE MIGHT BE NEEDED TO MAKE A LOT OF DILUTED LEMONADE).
THIS IS USUALLY WHAT WE ARE LOOKING FOR
C2 = CONCENTRATION OF DILUTED REAGENT (STRENGTH OF WHAT WE WANT TO MAKE IN % OR M)
V2 = VOLUME OF DILUTED REAGENT (THE TOTAL VOLUME (L, mL, uL, dL) OF THE REAGENT THAT WE ARE TRYING TO MAKE)
C1 = CONCENTRATION OF WHAT WE HAVE = 70%
I KNOW THAT THIS IS WHAT I HAVE BECUASE THIS IS WHAT I AM USING TO "PREPARE A 4000mL, 5% SOLUTION" - THAT IS WHAT THE QUESTION SAID. THEREFORE I MUST HAVE IT SOMEWHERE IN THE LABORATORY
V1 = THIS IS WHAT WE NEED TO FIGURE OUT. HOW MUCH OF MY CONCENTRATE THAT I HAVE DO I NEED TO TAKE OUT OF THE BOTTLE TO MAKE A DILUTED FORM OF THE SOLUTION
C2 = CONCENTRATION OF WHAT I AM TRYING TO PREPARE= 5%
V2 = VOLUME OF TOTAL SOLUTION I WAS TOLD TO PREPARE = 4000mL
V1 = (C2 X V2) / C1
V1 = (5% x 4000ml) / 70%
5 x 4000 = 20000
20000/70 = 285.71mL
9.
HOW MUCH OF A 10% ALCOHOL SOLUTION IS USED TO PREPARE A 200mL, 5% ALCOHOL SOLUTION
Correct Answer
C. 100
Explanation
AN INITIAL CONCENTRATION HAS BEEN GIVEN, THEREFORE THE EQUATION TO BE USED IS
C1 X V1 = C2 X V2
FROM THE ABOVE EQUATION,
V1 = (C2 X V2)/C1
THE #1 REPRESENTS CONCENTRATE SIDE OF THE EQUATION (WHAT WE HAVE)
THE #2 REPRESENTS DILUTED SIDE OF TEH EQUATION (WHAT WE WANT TO MAKE)
C1 = THE CONCENTRATION OF THE CONCENTRATE
V1 = THE VOLUME (L, GALLONS, mL, uL, dL) OF THE CONCENTRATE NEEDED TO MAKE OUR DILUTION (FOR EXAMPLE TWO CUPS OR GALLONS OR mL, OR TEASPOONS OF FROZEN CONCENTRATED LEMONADE MIGHT BE NEEDED TO MAKE A LOT OF DILUTED LEMONADE).
THIS IS USUALLY WHAT WE ARE LOOKING FOR
C2 = CONCENTRATION OF DILUTED REAGENT (STRENGTH OF WHAT WE WANT TO MAKE IN % OR M)
V2 = VOLUME OF DILUTED REAGENT (THE TOTAL VOLUME (L, mL, uL, dL) OF THE REAGENT THAT WE ARE TRYING TO MAKE)
C1 = CONCENTRATION OF WHAT WE HAVE = 10%
I KNOW THAT THIS IS WHAT I HAVE BECUASE THIS IS WHAT I AM USING TO "PREPARE A 200mL, 5% SOLUTION" - THAT IS WHAT THE QUESTION SAID. THEREFORE I MUST HAVE IT SOMEWHERE IN THE LABORATORY
V1 = THIS IS WHAT WE NEED TO FIGURE OUT. HOW MUCH OF MY CONCENTRATE THAT I HAVE DO I NEED TO TAKE OUT OF THE BOTTLE TO MAKE A DILUTED FORM OF THE SOLUTION
C2 = CONCENTRATION OF WHAT I AM TRYING TO PREPARE= 5%
V2 = VOLUME OF TOTAL SOLUTION I WAS TOLD TO PREPARE = 200mL
V1 = (C2 X V2) / C1
V1 = (5% x 200ml) / 10%
5 x 200 = 1000
1000/10 = 100mL
10.
A 4 L OF 20% ALCOHOL IS NEEDED, HOW MUCH 50% ALCOHOL IS REQUIRED TO MAKE 20% ALCOHOL
Correct Answer
A. 1.6L
Explanation
AN INITIAL CONCENTRATION HAS BEEN GIVEN, THEREFORE THE EQUATION TO BE USED IS
C1 X V1 = C2 X V2
FROM THE ABOVE EQUATION,
V1 = (C2 X V2)/C1
THE #1 REPRESENTS CONCENTRATE SIDE OF THE EQUATION (WHAT WE HAVE)
THE #2 REPRESENTS DILUTED SIDE OF TEH EQUATION (WHAT WE WANT TO MAKE)
C1 = THE CONCENTRATION OF THE CONCENTRATE
V1 = THE VOLUME (L, GALLONS, mL, uL, dL) OF THE CONCENTRATE NEEDED TO MAKE OUR DILUTION (FOR EXAMPLE TWO CUPS OR GALLONS OR mL, OR TEASPOONS OF FROZEN CONCENTRATED LEMONADE MIGHT BE NEEDED TO MAKE A LOT OF DILUTED LEMONADE).
THIS IS USUALLY WHAT WE ARE LOOKING FOR
C2 = CONCENTRATION OF DILUTED REAGENT (STRENGTH OF WHAT WE WANT TO MAKE IN % OR M)
V2 = VOLUME OF DILUTED REAGENT (THE TOTAL VOLUME (L, mL, uL, dL) OF THE REAGENT THAT WE ARE TRYING TO MAKE)
C1 = CONCENTRATION OF WHAT WE HAVE = 50%
I KNOW THAT THIS IS WHAT I HAVE BECAUSE THIS IS WHAT I AM USING TO "PREPARE A 4L OF 20% SOLUTION" - I KNOW THIS BECAUSE IT IS IN THE QUESTION. THEREFORE I PROBABLY HAVE IT IN THE LABORATORY
V1 = THIS IS WHAT WE NEED TO FIGURE OUT. HOW MUCH OF MY CONCENTRATE THAT I HAVE DO I NEED TO TAKE OUT OF THE BOTTLE TO MAKE A DILUTED FORM OF THE SOLUTION
C2 = CONCENTRATION OF WHAT I AM TRYING TO PREPARE= 20%
V2 = VOLUME OF TOTAL SOLUTION I WAS TOLD TO PREPARE = 4L
V1 = (C2 X V2) / C1
V1 = (20% X 4L) / 50%
20 x 4 = 80
80/50 = 1.6L
11.
A PROCEDURE CALLS FOR 20% ACETIC ACID. 100mL ARE NEEDED. HOW MUCH ACETIC ACID IS NEEDED
Correct Answer
B. 20mL
Explanation
THIS IS A DILUTION QUESTION, WHERE WE WERE NOT GIVEN AN INITIAL CONCENTRATION. THEREFORE, WE WOULD USE THE EQUATION
a/ (a+b) x total volume.
typically we are mixing two fluids lets say a and b to make a total solution (a+b)
a is the volume or number of parts a
b is the volume or number of parts b
a+b represents the total solution
for percent solutions
a % means "a parts out of 100 total parts"
a+b which represents total parts =100 (the question does not have to give us b SINCE WE HAVE TOTAL ALREADY)
a/(a+b) = a/100
a/(a+b) x total volume (for percent) = a/100 x total volume.
a/100 = 20/100, total volume is 100mL.
the volume of bleach concentrate needed is 20/100 x 100mL
20 divide by 100 = 0.20
0.20 multiplied by 100 = 20mL
12.
A 8 L OF 20% ALCOHOL IS NEEDED, HOW MUCH 50% ALCOHOL IS REQUIRED TO MAKE 20% ALCOHOL
Correct Answer
A. 3.2L
Explanation
AN INITIAL CONCENTRATION HAS BEEN GIVEN, THEREFORE THE EQUATION TO BE USED IS
C1 X V1 = C2 X V2
FROM THE ABOVE EQUATION,
V1 = (C2 X V2)/C1
THE #1 REPRESENTS CONCENTRATE SIDE OF THE EQUATION (WHAT WE HAVE)
THE #2 REPRESENTS DILUTED SIDE OF TEH EQUATION (WHAT WE WANT TO MAKE)
C1 = THE CONCENTRATION OF THE CONCENTRATE
V1 = THE VOLUME (L, GALLONS, mL, uL, dL) OF THE CONCENTRATE NEEDED TO MAKE OUR DILUTION (FOR EXAMPLE TWO CUPS OR GALLONS OR mL, OR TEASPOONS OF FROZEN CONCENTRATED LEMONADE MIGHT BE NEEDED TO MAKE A LOT OF DILUTED LEMONADE).
THIS IS USUALLY WHAT WE ARE LOOKING FOR
C2 = CONCENTRATION OF DILUTED REAGENT (STRENGTH OF WHAT WE WANT TO MAKE IN % OR M)
V2 = VOLUME OF DILUTED REAGENT (THE TOTAL VOLUME (L, mL, uL, dL) OF THE REAGENT THAT WE ARE TRYING TO MAKE)
C1 = CONCENTRATION OF WHAT WE HAVE = 50%
I KNOW THAT THIS IS WHAT I HAVE BECAUSE THIS IS WHAT I AM USING TO "PREPARE A 4L OF 20% SOLUTION" - I KNOW THIS BECAUSE IT IS IN THE QUESTION. THEREFORE I PROBABLY HAVE IT IN THE LABORATORY
V1 = THIS IS WHAT WE NEED TO FIGURE OUT. HOW MUCH OF MY CONCENTRATE THAT I HAVE DO I NEED TO TAKE OUT OF THE BOTTLE TO MAKE A DILUTED FORM OF THE SOLUTION
C2 = CONCENTRATION OF WHAT I AM TRYING TO PREPARE= 20%
V2 = VOLUME OF TOTAL SOLUTION I WAS TOLD TO PREPARE = 8L
V1 = (C2 X V2) / C1
V1 = (20% X 8L) / 50%
20 x 8 = 160
160/50 = 3.2L
13.
HOW MUCH BLEACH IS NEEDED TO MAKE A 160mL, 1 :20 dilution of BLEACH SOLUTION
Correct Answer
A. 8mL
Explanation
THIS IS A DILUTION QUESTION, WHERE WE WERE NOT GIVEN AN INITIAL CONCENTATION. THEREFORE, WE WOULD USE THE EQUATION
dilution type is ratio (part:total) =(parts out of total) = (1 part bleach out of 20 parts total)
lets say
a(substance of interest) is bleach and b is water
a = 1, a+b = 20
(we used "a" to represent bleach and not water because bleach is our substance of interest, the liquid b used to dilute is not of interest to us)
(we know that bleach is our substance of interest because we are making a bleach solution and not a water solution - the question told us that)
ratios are written as "part : total"
this means ratio (a : total)
ratio "a:total" can be rewritten as "a parts / total parts"
volume required = a parts/ (total parts) x total volume.
a/(total) = 1/(20)
total volume is 160mL.
the volume of bleach concentrate needed is (1/20) x 160mL
1 divided by 20= 0.05
0.05 x 160mL = 8mL
14.
HOW MUCH BLEACH IS NEEDED TO MAKE A 400mL BLEACH SOLUTION WITH 1 PARTS BLEACH AND 4 PARTS WATER
Correct Answer
C. 80mL
Explanation
THIS IS A DILUTION QUESTION, WHERE WE WERE NOT GIVEN AN INITIAL CONCENTATION. THEREFORE, WE WOULD USE THE EQUATION
a/ (a+b) x total volume.
lets say
a(substance of interest) is bleach and b is water
a = 1, b = 4, a+b = 5.
(we used "a" to represent bleach and not water because bleach is our substance of interest)
(we know that bleach is our substance of interest because we are making a bleach solution and not a water solution - the question told us that)
a/(a+b) = 1/(1+4) = 1/5
total volume is 4000mL.
the volume of bleach concentrate needed is (1/5) x 400mL
1 divided by 5 =0.2
0.2 x 400mL = 80mL
15.
HOW COULD A 1 TO 25 DILUTION OF BLOOD BE PREPARED
Correct Answer
A. ONE PART BLOOD MIXED WITH 24 PARTS SALINE
Explanation
A 1 to 25 dilution of blood can be prepared by mixing one part of blood with 24 parts of saline. This means that for every one unit of blood, there should be 24 units of saline. This dilution is used to reduce the concentration of blood in a sample, making it easier to analyze or perform certain tests. By diluting the blood with saline, the volume of the sample is increased while maintaining the appropriate ratio of blood to saline.
16.
HOW COULD A 1:10 DILUTION OF SERUM BE PREPARED?
Correct Answer
B. ONE PART SERUM, NINE PART SALINE
Explanation
A 1:10 dilution of serum can be prepared by mixing one part of serum with nine parts of saline. This means that for every one unit of serum, nine units of saline are added to create a total volume of ten units. This dilution is commonly used in laboratory settings to reduce the concentration of a substance, in this case, serum, while maintaining the overall volume.
17.
WHAT IS THE DILUTION WHEN 1mL OF SERUM IS DILUTED TO A TOTAL VOLUME OF 50mL
Correct Answer
B. 1/50
Explanation
THIS IS A DILUTION OD SERUM SUCH THAT 1ML SERUM WAS ADDED TO A DILUENT LIKE SALINE (49mL) TO GIVE US A TOTAL VOLUME OF 50mL
DILUTION = PARTS/TOTAL OR a/(a+b) -------a = part, a+b = part a+ part b = total
a =VOLUME OF SERUM ONLY (PART OF TOTAL VOLUME)= 1ML SERUM
a+b = TOTAL volume (SERUM AND A DILUENT) = 50ml
dilution = part /total
DILUTION = 1/50mL
18.
WHAT IS THE DILUTION WHEN 1mL OF SERUM IS DILUTED TO A TOTAL VOLUME OF 50mL
Correct Answer
B. 1/50
Explanation
THIS IS A DILUTION OD SERUM SUCH THAT 1ML SERUM WAS ADDED TO A DILUENT LIKE SALINE (49mL) TO GIVE US A TOTAL VOLUME OF 50mL
DILUTION = PARTS/TOTAL OR a/(a+b) -------a = part, a+b = part a+ part b = total
a =VOLUME OF SERUM ONLY (PART OF TOTAL VOLUME)= 1ML SERUM
a+b = TOTAL volume (SERUM AND A DILUENT) = 50ml
dilution = part /total
DILUTION = 1/50mL
19.
WHAT IS THE DILUTION WHEN 2mL OF SERUM IS PLACED IN 23mL OF SALINE
Correct Answer
B. 2/25
Explanation
THIS IS A DILUTION OF SERUM SUCH THAT 2ML SERUM WAS ADDED TO A SALINE (23mL) TO GIVE US A TOTAL VOLUME OF 25mL
DILUTION = PARTS/TOTAL OR a/(a+b) -------a = part, a+b = part a+ part b = total
a =VOLUME OF SERUM ONLY (PART OF TOTAL VOLUME)= 2mL SERUM
b = VOLUME OF SALINE (LIQUID USED TO DILUTE OUR SUBSTANCE OF INTEREST) = 23mL
a+b = TOTAL volume (SERUM AND A DILUENT) = 25ml
dilution = part /total
DILUTION = 2/25mL
20.
WHAT IS THE DILUTION WHEN 2mL OF SERUM IS DILUTED TO A TOTAL VOLUME OF 25mL
Correct Answer
C. 2/25
Explanation
THIS IS A DILUTION OF SERUM SUCH THAT 2ML SERUM WAS ADDED TO A DILUENT LIKE SALINE (23mL) TO GIVE US A TOTAL VOLUME OF 25mL
DILUTION = PARTS/TOTAL OR a/(a+b) -------a = part, a+b = part a+ part b = total
a =VOLUME OF SERUM ONLY (PART OF TOTAL VOLUME)= 2ML SERUM
a+b = TOTAL volume (SERUM AND A DILUENT) = 25ml
dilution = part /total
DILUTION = 2/25
21.
I WAS TOLD TO EXPLAIN HOW I WOULD SET UP AN EQUATION FOR HOW MUCH ALCOHOL IS NEEDED TO MAKE A 10% SOLUTION FOR ANY GIVEN VOLUME. WHICH OF THE FOLLOWING IS TRUE
Correct Answer
D. (10/100) x TOTAL VOLUME
Explanation
VOLUME OF ALCOHOL NEEDED = a/a+b x TOTAL VOLUME
10 % = 10 parts out of 100 total parts.
such that
PART "a" = 10 (alcohol only)
TOTAL "a+b" = 100 (alcohol plus dilution fuid)
EQUATION FOR VOLUME NEEDED =
a/a+b x TOTAL VOLUME
AFTER SUBSTITUTING VALUES INTO THE EQUATION,
VOLUME NEEDED = (10/100) x TOTAL VOLUME