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Mademuasel [1]
3 years ago
12

In 1930 the american physicist ernest lawrence designed the first cyclotron in berkeley, california. in 1937 lawrence bombarded

a molybdenum-96 target with deuterium ions (2h), producing for the first time an element not found in nature. part a what was this element? express your answer as a chemical symbol without mass or atomic numbers.
Chemistry
1 answer:
gregori [183]3 years ago
8 0
In, 1937 Lawrence, in operating his cyclotron, bombarded a molybdenum-96 foil with deuterium ions (2h), producing for the first time an element not found in nature. He was initially unaware that the radioactivity produced by the "bombarded foil" was not from molybdenum but from a new, artificial element. It was his cooperation with Italian-American physicist <span>Emilio Segrè </span>that allowed the new element to be discovered. The answer is Technetium: Tc
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The space shuttle starts at rest and must reach a velocity of +10,000 m/s (22,000 miles/hour). The acceleration of the space shu
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7 0
2 years ago
Solution C is a 1.00 L buffer solution that is 1.420 M in acetic acid and 0.67 M in sodium acetate. Acetic acid has a pKa of 4.7
Maslowich

Answer:

The correct answer is 0.10.

Explanation:

Based on the given question, in a buffer solution of 1 liter, the molarity of acetic acid is 1.420 M and the molarity of sodium acetate is 0.67. The pKa value of acetic acid given is 4.74, now the pH of buffer is,  

pH of buffer = pKa + log ([CH3COONa]/[CH3COOH])

= 4.74 + log (0.67/1.420)

= 4.74 + (-0.326)

= 4.41  

Now 0.10100 mol of HCl is added, the HCl reacts with sodium acetate to give,  

CH3COONa + HCl = CH3COOH + NaCl

Now the concentration of CH3COONa becomes = 0.67-0.101 = 0.57 M, and the new concentration of CH3COOH becomes = 1.420 + 0.101 = 1.52 M

Now the new pH will be,  

= pKa + log (0.57/1.52)

= 4.74 + (-0.426)

= 4.31

The pH change is 4.41-4.31 = 0.10  

3 0
3 years ago
the compound diborane can be used as a rocket propellant. what is the percent composition of boron in diborane
Blababa [14]

Answer:

78.14 % B; 21.86 % H

Step-by-step explanation:

The formula of diborane is B₂H₆.

The masses of each element are:

2B  = 2 × 10.81    = 21.62    u

6H = 6 ×   1.008 = <u>  6.048  u </u>

             TOTAL =  27.67    u


% B = 21.62/27.67 × 100

        = 78.14 %

% H = 6.048/ 27.67

        = 21.86 %

3 0
3 years ago
Read 2 more answers
Vanillin, a flavoring agent, is made up of carbon, hydrogen, and Oxygen atoms. When a sample of Vanillin weighing 2.500g burns i
kirza4 [7]
To determine the empirical formula of the compound given, we need to determine the ratio of each element in the compound. To do that, we need to know the amount of carbon, hydrogen and oxygen atoms in the compound. We determine these from the given amounts of the products after burning. 

Given:
2.5 g vanillin
5.79 g CO2
1.18 g H2O

Solution:

mol C = 5.79 g CO2 ( 1 mol CO2 / 44.01 g CO2) ( 1 mol C / 1 mol CO2) = 0.132 mol C

mol H = 1.18 g H2O ( 1 mol g H2O / 18.02 g H2O) ( 2 mol H / 1 mol H2O) = 0.131 mol H

We convert them into grams,
0.132 mol C  (12.01 g / 1 mol) = 1.59 g
0.131 mol H (1.01 g / 1 mol) = 0.132 g
mass of C and H in vanillin = 1.722 g
mass of O = 2.5 - 1.722 = 0.778 g O

mol O = 0.778 g O ( 1 mol O / 16 g ) = 0.049 mol O

Dividing the number of moles of each element with the smallest value of number of mole, we will have the empirical formula:

         moles                    ratio
C       0.132     / 0.049      2.69 x 3 = 8
H       0.131     / 0.049      2.67 x 3 = 8
O       0.049    / 0.049         1   x 3 = 3

The empirical formula would be C8H8O3.

6 0
3 years ago
Most of an atom's volume is found:
Rus_ich [418]

Answer:

most of its mass is in the nucleus

Explanation:

the nucleus consists of protons and nutrons

8 0
3 years ago
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