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dimaraw [331]
2 years ago
14

A substance decays so that the amount a of the substance left after t years is given by: a = a 0 · (0.9) t , where a 0 is the or

iginal amount of the substance. what is the half-life (the amount of time that it takes to decay to half the original amount) of this substance rounded to the nearest tenth of a year?
Chemistry
1 answer:
Dennis_Churaev [7]2 years ago
3 0

I think the correct form of the equation is given as:

a = a0 * (0.9)^t

where t is an exponent of 0.9 since this is an exponential decay of 1st order reaction

 

Now to solve for the half life, this is the time t in which the amount left is half of the original amount, therefore that is when:

a = 0.5 a0

 

Substituting this into the equation:

0.5 a0 = a0 * (0.9)^t

0.5 = (0.9)^t

Taking the log of both sides:

t log 0.9 = log 0.5

t = log 0.5 / log 0.9

t = 6.58 years

 

Answer:

half life = 6.58 years

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A laboratory utilizes a mixture of 10% dimethyl sulfoxide (DMSO) in the freezing and long-term storage of embryonic stem cells.
Mars2501 [29]

Answer:

The correct answer is "1.0100".

Explanation:

Let the volume of mixture be 100 ml.

then,

The volume of DMSO will be 10 mL as well as that of water will be 90 mL.

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= 10\times 1.1004

= 11.004 \ g

The total mass of mixture will be:

= 90+11.004

= 101.004 \ g

Density of mixture will be:

= \frac{Mass}{Volume}

= \frac{101.004}{100}

= 1.01004 \ g/mL

hence,

Specific gravity of mixture will be:

= \frac{Density \ of \ mixture}{Density \ of \ water}

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2 years ago
How many milliliters of 0.200 M NH4OH are needed to react with 12.0 mL of 0.550 M FeCl3?
trapecia [35]

Answer:

9.9 ml of 0.200M NH₄OH(aq)

Explanation:

3NH₄OH(Iaq) + FeCl₃(aq) => NH₄Cl(aq) + Fe(OH)₃(s)

?ml of 0.200M NH₄OH(aq) reacts completely with  12ml of 0.550M FeCl₃(aq)

1 x Molarity NH₄OH x Volume Am-OH Solution(L) = 2 x Molarity FeCl₃ x Volume FeCl₃ Solution

1(0.200M)(Vol Am-OH Soln) = 3(0.550M)(0.012L)

=> Vol Am-OH Soln = 3(0.550M)(0.012L)/1(0.200M) = 0.0099 Liter = 9.9 milliliters  

5 0
2 years ago
The volume of a gas at 7.00°c is 49.0 ml. if the volume increases to 74.0 ml and the pressure is constant, what will the tempera
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Using charles law
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v1=49ml
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0.175t2=74
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m_a_m_a [10]

Answer:

i would say sensory memory, aka muscle memory.

Explanation:

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kompoz [17]
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