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dedylja [7]
2 years ago
11

Which of the following tools could have become cross-contaminated during the experiment if you had not cleaned them carefully be

tween successive tests?
A. Spoon

B. Beaker

C. Stirring Rod

D. Graduated Cylinder

E. Distilled water in a spray bottle
Chemistry
2 answers:
guajiro [1.7K]2 years ago
8 0

Answer:

A. Spoon, B. Beaker, C. Stirring Rod, D. Graduated Cylinder

Explanation:

Elanso [62]2 years ago
3 0

Explanation:

When we are using spoon, beaker, stirring rod and graduated cylinder then they directly come in contact with the chemical we are using. Hence, if they are not washed thoroughly then chemicals remain deposited over them.

As a result, when successive test are performed using the same contaminated apparatuses then we do not get the desired results.

Whereas distilled water in a spray bottle if poured without touching or coming in contact with any kind of chemicals.

Hence, we can conclude that spoon, beaker, stirring rod and graduated cylinder are the tools that could have become cross-contaminated during the experiment if you had not cleaned them carefully between successive tests.

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Magnesium has an atomic mass of 24.3. there are two isotopes of magnesium - one contains 12 neutrons and the other contains 13 n
Juli2301 [7.4K]
So what we know:
-Atomic Mass = Protons + Neutrons
-Atomic Number is the number of protons

Magnesium's atomic number is 12, so the natural occurring isotope for magnesium is Mg-12 (12 protons and 12 neutrons). Added up we have an atomic mass of 24 amu. Which means if we added one neutron in Mg-13, our atomic mass would be 25 amu.

We can use the equation:
(amu of isotope 1)x + (amu of isotop 2)(x-1) = Average atomic mass
where isotope 1 is the fractional abundance we're solving for.

Plugged in it looks like this:
24x + 25(1-x) = 24.3

Now to solve for x:
24x + 25 - 25x = 24.3
   -x + 25 = 24.3
        -x = -.7
         x = .7

So in this case, the fractional abundance of Mg-12 would be .7, or 70%.<span />
3 0
2 years ago
How many moles of BCl3 are needed to produce 10.0 g of HCl(aq) in the following reaction? (HCl molar mass is 36.46 g/mol).
Scilla [17]

Answer:

Moles of BCl₃ needed = 0.089 mol

Explanation:

Given data:

Moles of BCl₃ needed = ?

Mass of HCl produced = 10.0 g

Solution:

Chemical equation:

BCl₃ + 3H₂O  →     3HCl + B(OH)₃

Number of moles of HCl:

Number of moles = mass/molar mass

Number of moles = 10.0 g/ 36.46 g/mol

Number of moles = 0.27 mol

Now we will compare the moles of HCl with BCl₃.

               HCl             :           BCl₃

                 3               :             1

             0.27             :            1/3×0.27 = 0.089 mol

6 0
2 years ago
A 100-W lightbulb is placed in a cylinder equipped with a moveable piston. The lightbulb is turned on for 0.020 h, and the assem
nasty-shy [4]

Answer: The workdone W = 505J

Explanation:

Applying the pressure-volume relationship

W= - PΔV

Where negative sign indicates the power is being delivered to the surrounding

W = - 1.0atm * ( 5.88 - 0.9)L

= - 1.0atm * (4.98)

W = -4.98 atmL

Converting to Joules

1atmL = 101.325J

-4.98atmL = x joules.

Work done in J = -4.98 * 101.325

W= -505J

Therefore the workdone is -505J

5 0
2 years ago
Why are the concentrations of [H3O+] and [OH−] equal in pure water?
kotegsom [21]

Answer : The correct option is, (A) [H_3O^+]=[OH^-] because one of each is produced every time an [H^+] transfers from one water molecule to another.

Explanation :

As we know that, when the two water molecule combine to produced hydronium ion and hydroxide ion.

The balanced reaction will be:

HOH+HOH\rightarrow H_3O^++OH^-

Acid : It is a substance that donates hydrogen ion when dissolved in water.

Base : It is a substance that accepts hydrogen ion when dissolved in water.

From this we conclude that, the hydrogen ion are transferred from one water molecule to the another water molecule to form hydronium ion and hydroxide ion. In this reaction, one water molecule will act as a base and another water molecule will act as an acid.

Hence, the correct option is, (A)

3 0
2 years ago
A student described two properties of a substance shown below which of the following is true about the two properties described
mel-nik [20]

Answer:

B

Explanation:

catches fire easily, there is a chemical in the substance that reacts to the flame, and a key to it being a chemical property is when exposed to other substances, there is a chemical in the other substances that makes it chemically react

7 0
2 years ago
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