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Leona [35]
3 years ago
6

Which statement describes a physical change? *

Chemistry
1 answer:
xxMikexx [17]3 years ago
4 0
B. The surface of a silver cup turns black when it is exposed to air.
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Which reactant in each of the following pairs is more nucleophilic? Explain.a. -NH2 or NH3b. H20 or CH3CO2-c. BF3 or F-d. (CH3)3
Anestetic [448]

Answer:

I^- or Cl^-

Explanation:

A nucleophile is any reagent that donates an unshared pair of electrons to form a new covalent bond. Nucleophiles are mostly bases also. Nucleophilicity is a kinetic property, it refers to the rate at which a nucleophile replaces a leaving group from an alkyl halide.

Looking at the options, Cl^- and I^- are the best nucleophiles among the options provided in the question.

3 0
3 years ago
What is the general formula for cycloalkenes.
maria [59]
C( n)H(2n) is the general formula, eg: Cyclohexane is C6H12
3 0
2 years ago
Read 2 more answers
what is the percent yield of NaCl if 31.0 g of CuCl reacts with excess NaNo3 to produce 21.2 g of NaCl
olchik [2.2K]
Percentage Yield = (Actual Yield ÷ Theoretical Yield) × 100  

The Actual Yield is given in the question as 21.2 g of NaCl.  However, in order to find the theoretical yield, you have to write a balanced equation and use the mole ratio to calculate the mass of NaCl that would be produced.

Balanced Equation:   CuCl + NaNO₃    →    NaCl + CuNO₃

Moles of CuCl = Mass of CuCl ÷ Molar Mass of CuCl
                         =  31.0 g ÷ (63.5 + 35.5)g/mol
                         = 0.31 mol

the mole ratio of CuCl to NaCl is 1  :  1,
∴ if moles of CuCl = 0.31  mol,

then moles of NaCl = 0.31 mol

Now, Mass of NaCl = Moles of NaCl × Molar Mass of NaCl
                                 =  0.31 mol × (23 + 35.5) g/mol
                                 =  18.32 g

⇒ the THEORETICAL Yield of NaCl, in this case, is 18.32 g.

Now, since Percentage Yield = (Actual Yield ÷ Theoretical Yield) × 100  

⇒ Percentage Yield of NaCl = (21.2g ÷ 18.32g) × 100  
                                                = 115.7 %


NOTE: Typically, the percentage yield of a reaction is less than 100%, however in a case where the mass of the substance is weighed with impurities, then that mass may be in excess of 100% as seen here.
4 0
3 years ago
F a sample of butene (C4H8) that has a mass of 136.6 g is combusted in excess oxygen, what is the mass of CO2 that is produced?
alukav5142 [94]

The balanced chemical reaction will be:

C4H8 + 6 O2 --> 4 CO2 + 4 H2O

We are given the amount of butene being combusted. This will be our starting point.

136.6 g C4H8 (1 mol  C4H8/ 56.11 g C4H8) (4 mol CO2/1 mol <span>C4H8</span>) ( 44.01 g CO2/ 1 mol CO2) = 428.6 g CO2
7 0
3 years ago
Read 2 more answers
Which of the following elements has the largest atomic radius
Olin [163]

Answer: Calcium

Explanation:

not 100% sure but i looked it up and got calcium. 99% sure.

8 0
2 years ago
Read 2 more answers
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