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White raven [17]
3 years ago
14

Define what is halflife​

Chemistry
1 answer:
zhuklara [117]3 years ago
8 0

Half-life is the time it takes for a substance to lose half of its pharmacological, physiological, or radiological activity.

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Keiko needs 100mL of a 5% acid solution for a science experiment. She has available a 1% solution and a 6% solution. How many mi
4vir4ik [10]

Answer:

Keiko should mix 20 mL 1% solution and 80 mL 6% solution for to make 100 mL 5% solution

Explanation:

There are 2 unknown values X= mL 6% solution and Y=1% solution. So, we need 2 equations:

1. Equation acid concentration. X mL 6% + Y mL 1% = 100 mL 5%

2. Equation solvent concentration X mL 94% + Y mL 99% = 100 mL 95%

When clearing X and Y :

(X mL 6%    +   Y mL 1%      =    100 mL 5%) (-15,7)

X mL 94%  +   Y mL 99%   =   100 mL 95%

_______________________________

 -                      Y  0.83       =   16.5

                        Y                =   19.9 mL 1% solution

Replace Y in anyone equation and X = 80 mL 6% solution

I hope to see been helpful

7 0
3 years ago
Read 2 more answers
A screw has 4 threads per centimeter and a circumference of 2 centimeters. The mechanical advantage of the screw is?
sashaice [31]
<span>The answer is 8. Hope this help!!!

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3 0
3 years ago
Read 2 more answers
Give the net ionic equation for the reaction (if any) that occurs when aqueous solutions of Al(C2H3O2)3 and LiNO3 are mixed. Giv
RSB [31]

Answer: No reaction occurs

Explanation:.

Spectator ions are defined as the ions which does not get involved in a chemical equation or they are ions which are found on both the sides of the chemical reaction present in ionic form.

The given chemical equation is:

Al(C_2H_3O_2)_3(aq)+3LiNO_3(aq)\rightarrow Al(NO_3)_3(aq)+3LiC_2H_3O_2(s)

The complete ionic equation is;

Al^{3+}(aq)+3C_2H_3O_2^-(aq)+3Li^+(aq)+3NO_3^-(aq)\rightarrow Al^{3+}(aq)+3NO_3^-(aq)+3Li^+(aq)+3C_2H_3O_2^-(aq)

The ions which are present on both the sides of the equation are are not involved in net ionic equation.

Hence, there is no net reaction.

5 0
3 years ago
Propanoic acid, ch3ch2cooh, has a pka =4.9. draw the structure of the conjugate base of propanoic acid and give the ph above whi
xenn [34]

Conjugate base of Propanoic acid (CH_{3}CH_{2}COOH is propanoate where -COOH group gets converted to -COO^{1-}. The structure of conjugate base of Propanoic acid is shown in the diagram.

The p^{H} above which 90% of the compound will be in this conjugate base form can be determined using Henderson's equation as propanoic acid is weak acid and it can form buffer solution on reaction with strong base.

p^{H}= p^{k_{a}+ log\frac{[Conjugate base]}{[acid]}=4.9+log\frac{90}{10}=5.85

As 90% conjugate base is present, so propanoic acid present 10%.

8 0
3 years ago
An alpha particle is equivalent to the nucleus of an atom of which element?(1 point)
Katyanochek1 [597]

Answer:

this is what i got

Explanation:

α-decay: When a radioactive nucleus disintegrates by emitting an αα-particle, the atomic number decreases by two and mass number decreases by four. Example: 88​Ra226→86​Rn222+2​He4.

3 0
2 years ago
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