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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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Acetylene burns in air according to the following equation: C2H2(g) + 5 2 O2(g) → 2 CO2(g) + H2O(g) ΔH o rxn = −1255.8 kJ Given
professor190 [17]

Answer:  -227 kJ

Explanation:

The balanced chemical reaction is,

C_2H_2(g)+\frac{5}{2}O_2(g)\rightarrow 2CO_2(g)+H_2O(g)

The expression for enthalpy change is,

\Delta H=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)]

\Delta H=[(n_{CO_2}\times \Delta H_{CO_2})+ n_{H_2O}\times \Delta H_{H_2O})]-[(n_{C_2H_2}\times \Delta H_{C_2H_2})+(n_{O_2}\times \Delta H_{O_2})]

where,

n = number of moles

\Delta H_{O_2}=0 (as heat of formation of substances in their standard state is zero

Now put all the given values in this expression, we get

-1255.8=[(2\times -393.5)+(1\times -241.8)]-[(1\times \Delta H_{C_2H_2})+(\frac{5}{2}\times 0)]

-1255.8=[(-787)+(-241.8)]-[(1\times \Delta H_{C_2H_2})+(0)]

\Delta H_{C_2H_2}=-227kJ

Therefore, the enthalpy change for C_2H_2 is -227 kJ.

7 0
2 years ago
How many grams of calcium cyanide (Ca(CN)2) are contained in 0.79 mol of calcium cyanide?
Allushta [10]
I dont know but do you know da wae brudda?


3 0
2 years ago
The volume of distilled water that should be added to 10.0 mL of 6.00 M HCl(aq) in order to prepare a 0.500 M HCl(aq) solution i
bija089 [108]

Answer:

110ml

Explanation:

<em>Using the dilution equation, C1V1 = C2V2</em>

<em>Where C1 is the initial concentration of solution</em>

<em>C2 is final concentration of solution</em>

<em>V1 is intital volume of solution</em>

<em>V2 is final volume of solution.</em>

From the question , C1=6M, C2=0.5M, V1=10ml, V2=?

V2 =\frac{C1V1}{C2}

V2 =\frac{10*6}{0.5}

V2 =120ml

volume of water added = final volume -initial volume

                                    = 120-10

                                   =110ml

3 0
2 years ago
A sample of 0.53 g of carbon dioxide was obtained by heating 1.31 g of calcium carbonate. what is the percent yield for this rea
Masja [62]

CaCO3(s) ⟶ CaO(s)+CO2(s) 

<span>
moles CaCO3: 1.31 g/100 g/mole CaCO3= 0.0131 </span>

<span>
From stoichiometry, 1 mole of CO2 is formed per 1 mole CaCO3, therefore 0.0131 moles CO2 should also be formed. 
0.0131 moles CO2 x 44 g/mole CO2 = 0.576 g CO2 </span>

Therefore:<span>
<span>% Yield: 0.53/.576 x100= 92 percent yield</span></span>

4 0
2 years ago
Read 2 more answers
At 10.°C, 20.g of oxygen gas exerts a pressure of 2.1atm in a rigid, 7.0L cylinder. Assuming ideal behavior, if the temperature
Alja [10]

Answer:

Final pressure = 2.3225 atm

Amontons’s law states that

At constant volume and number of molecules, the pressure of a given mass of gas is directly proportional to its temperature

Explanation:

Temperature causes increased excitement of gas molecules increasing the number of collisions with the walls of the container which is sensed as increase in pressure

Amontons’s law: P/T = Constant at constant V and n

That is P1/T1 = P2/T2

Where temperature is given in Kelvin

Hence T1 of 10°C = 273.15 + 10 = 283.15K

Also temperature T2 of 40°C = 313.15 K

Hence

P2 = (P1/T1)×T2 = (2.1/283.15)×313.15 = 2.3225 atm

3 0
2 years ago
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