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frosja888 [35]
3 years ago
13

The half-life of bismuth is 5 days. How much of a 100 gram sample will remain after 20 days?

Chemistry
1 answer:
sesenic [268]3 years ago
8 0
Half-life is the duration needed for a compound to decay into half of its initial weight. In this case, the initial weight is 100gram. The calculation for the final weight should be:

final weight= initial weight * (1/2)^(duration/half-life)
final weight= 100 grams * (1/2)^(20days/5 days)
final weight= 100 grams * (1/2)^(4)
final weight= 100 * 1/16= 100/16 gram= 6.25 grams

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Số hợp chất tố đa của nguyên tố này với nguyên tố khác theo hóa trị của nó
SVETLANKA909090 [29]

Answer:

Carbon

Explanation:

Carbon

5 0
2 years ago
A student is instructed to make 1 L of a 2.0 M solution of CaCl2 using dry salt. How should he do this?
Pachacha [2.7K]
<span>The student should follow following steps to make 1 L of </span>2.0 M CaCl₂.<span>
<span>
1. First he should calculate the number of moles of 2.0 M CaCl</span></span>₂ in 1 L solution.<span>

</span>Molarity of the solution = 2.0 M<span>
Volume of solution which should be prepared = 1 L

Molarity = number of moles / volume of the solution

Hence, number of moles in 1 L = 2 mol

2. Find out the mass of dry CaCl</span>₂ in 2 moles.<span>

moles = mass / molar mass

Moles of CaCl₂ = 2 mol</span><span>
Molar mass of CaCl₂ = </span><span>110.98 g/mol

Hence, mass of CaCl</span>₂ = 2 mol x <span>110.98 g/mol
                                     = 221.96 g

3. Weigh the mass accurately 

4. Then take a cleaned and dry1 L volumetric flask and place a funnel top of it. Then carefully add the salt into the volumetric flask and finally wash the funnel and watch glass with de-ionized water. That water also should be added into the volumetric flask.

5. Then add some de-ionized water into the volumetric flask and swirl well until all salt are dissolved.

<span>6. Then top up to mark of the volumetric flask carefully. 
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</span>
7. As the final step prepared solution should be labelled.
4 0
3 years ago
A florist prepares a solution of nitrogen-phosphorus fertilizer by dissolving 5.66 g of NH₄NO₃ and 4.42 g of (NH₄)₃ PO₄ in enoug
Alexandra [31]

In finding the molarity of a solution, we use the following formula:

M=moles soluteL solution

What is Molarity?

The number of moles of the solute is calculated by dividing the mass of the solute by its molar mass.

<h3 />

The molar mass of  NH4NO3 and (NH4)3PO4 are  80.043 g/mol and 149.0867 g/mol, respectively.

molesNH+4inNH4NO3=5.66 g80.043 g/mol×1molNH+41molNH4NO3=0.0707 mol

molesNH+4in(NH4)3PO4=4.42 g149.0867 g/mol×3molNH+41mol(NH4)3PO4=0.0889 mol

total molesNH+4=0.0707 mol+0.0889 mol=0.1596 mol

molesPO3−4in(NH4)3PO4=4.42 g149.0867 g/mol×1molPO3−41mol(NH4)3PO4=0.0296 mol

[NH+4]=0.1596 mol20.0 L=7.98×10−3 M NH+4

[PO3−4]=0.0296 mol20.0 L=1.48×10−3 M PO3−4

Therefore, [PO3−4]\\ has a molarity of  1.48×10−3 M PO3−

To learn more about Molarity click on the link below:

brainly.com/question/19943363

#SPJ4

5 0
1 year ago
Convert -32 F into K
Afina-wow [57]

Answer:

-32 Fahrenheit converts to 237.594 Kelvin

4 0
3 years ago
A 2.17 gm sample barium reacted completely with water what is the equation for the reaction how many milliliters of dry H2 evole
vaieri [72.5K]

Answer:

400 mL

Explanation:

Given data:

Mass of barium = 2.17 g

Pressure = 748 mmHg (748/760 = 0.98 atm)

Temperature = 21 °C ( 273+ 21 = 294k)

Milliliters of H₂ evolved = ?

Solution:

chemical equation:

Ba + 2H₂O →  Ba(OH)₂ + H₂

Number of moles of barium:

Number of moles = mass/ molar mass

Number of moles = 2.17 g / 137.327 g/mol

Number of moles = 0.016 mol

Now we  will compare the moles of barium with H₂.

                       Ba        :       H₂

                         1         :         1

                  0.016        :     0.016

Milliliters of H₂:

PV = nRT

V = nRT/P

V = 0.016 mol ×  0.0821 atm. mol⁻¹.k⁻¹.L×294 k/0.98 atm

V = 0.39 atm. L/0.98 atm

V = 0.4 L

L to mL

0.4 × 1000 = 400 mL

8 0
3 years ago
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