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galina1969 [7]
3 years ago
7

Americium-241 is a radioactive substance used in smoke detectors. The half life of americium is 432 years. If a smoke detector i

nitially contains 1 gram of Americium 241, how much will remain in 432 years? A) 0.5g B) 1.0g C) 1.5g D) 2.0g
Chemistry
1 answer:
aksik [14]3 years ago
7 0
<span>The half life of americium is 432 years. That means that after 432 years only half(1/2) of initial amount will be left.
If we had 1 g, then after 432 years we will have only half of it.
1g*1/2=1/2 g=0.5 g
Answer is </span><span>A) 0.5g</span>
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A chemist prepares a solution by dissolving 0.3 mole of CaCl2 in enough water to make 1000 mL of solution. What is the molar con
Rasek [7]
CaCl_{2} dissolves in water to give Ca^{2+} and Cl^{-} ions according to the following reaction:

CaCl_{2}  -------->  Ca^{2+}  + 2Cl^{-}

So, according to the above reaction, 1 mole of CaCl_{2} produce 2 moles of Cl^{-} ion,

So, 0.3 mole will give = 0.3 x 2 = 0.6 moles of  Cl^{-} ion

So, Molar concentration = \frac{0.6moles}{1L} = 0.6

Note: 1L = 1000mL 

7 0
2 years ago
What color is used to represent crust that is 135 million years old
Lostsunrise [7]
Orange i believe so or if not blue
8 0
3 years ago
If you wanna get oil to 180 celcius when it starts at 20 how many units of thermal energy is needed?
Zarrin [17]

Answer:

The thermal energy (heat) needed, to raise the temperature of oil of mass  'm' kilogram and specific heat capacity 'c' from 20°C to 180°C  is  160·m·c joules

Explanation:

The heat capacity, 'C', of a substance is the heat change, ΔQ, required by a given mass, 'm', of the substance to produce a unit temperature change, ΔT

∴ C = ΔQ/ΔT

ΔQ = C × ΔT

C = m × c

Where;

c = The specific heat capacity

ΔT = The temperature change = T₂ - T₁

∴ ΔQ = m × c × ΔT

Therefore, the thermal energy (heat) needed, ΔQ, to raise the temperature of oil of mass 'm' kilogram and specific heat capacity, 'c' from 20°C to 180°C  is given as follows;

ΔQ = m × c × (180° - 20°) = 160° × m·c

ΔQ = 160·m·c joules

7 0
2 years ago
An aqueous solution is 0.467 m in hcl. what is the molality of the solution if the density is 1.23 g/ml?
Reika [66]
Answer:
molarity = 0.385 moles/kg

Explanation:
Assume that the volume of the aqueous solution given is 1 liter = 1000 ml
Now, density can be calculated using the following rule:
density = mass / volume
Therefore:
mass = density * volume = 1.23 * 1000 = 1230 grams
Now, 0.467 m/L * 1L = 0.467 moles of HCl
We will get the mass of the 0.467 moles of HCl as follows:
mass = molar mass * number of moles = (1+35.5)*0.467 = 17.0455 grams
Now, we have the mass of the solution (water + HCl) calculated as 1230 grams and the mass of the HCl calculated as 17.0455 grams. We can use this information to get the mass of water as follows:
mass of water = 1230 - 17.0455 = 1212.9545 grams
Finally, we will get the molarity as follows:
molarity = number of moles of solute / kg of solution
molarity = (0.467) / (1212.9594*10^-3)
molarity = 0.385 mole/kg 

Hope this helps :)

5 0
3 years ago
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8 0
3 years ago
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