All categories

2 years ago

Calcium-45 has a half-life of 162.7 days. if four half-lives have elapsed, how much time has passed?

Chemistry

2 answers:

enyata [817]2 years ago

7 0

Answer:

650.8 days

Explanation:

if the half-life is 162.7 days and the number of half-life days has elapsed 4 times.

To know the number of days that have passed we must multiply the half-life by 4

$4(162.6)= 650.8 days$

stiv31 [10]2 years ago

3 0

Half-life is the time required for a quantity to reduce to half its initial value. If four half-lives have elapsed for calcium-45, then it would be 4x162.7 = 650.8 days have passed. Hope this answers the question. Have a nice day. Feel free to ask more questions.

You might be interested in

During an experiment a thermometer was placed in a beaker containing hydrogen peroxide. The following observations were recorded

Rudiy27

Answer:

Chemical

Explanation:

The change was chemical, because it can no longer be returned to the original form. You cannot get back the bubbles or fizz from the air.

3 0

2 years ago

Read 2 more answers

A box has 2 cm length, 3 cm width and 2 cm height. What is its volume? *

Valentin [98]

12cm cubed.
Formula is length x width x height and in this case it would be 2x3x2 which equals 23

3 0

3 years ago

Read 2 more answers

Wine goes bad soon after opening because the ethanol ch3ch2oh in it reacts with oxygen gas o2 from the air to form water h2o and

maks197457 [2]

1) Chemical reaction

CH3 CH2 OH + O2 ---> CH3COOH + H2O

It is balanced

2) Molar ratios

1 mol CH3 CH2OH : 1 mol O2 : 1 mol CH3COOH : 1 mol H2O

3) Conversion of 7.6 grams of ethanol to moles

Molar mass of CH3CH2OH = 2 * 12g/mol + 6 * 1 g/mol + 16 g/mol = 46 g/mol

moles = mass / molar mass = 7.6 g / 46g/mol = 0.165 mol

4) Use of proportions with the molar ratios:

1mol CH3CH2OH / 1mol O2 = 0.165 mol CH3CH2OH / x => x = 0.165 mol CH3CH2OH.

5) Conversion of 0.165 mol O2 to grams

mass in grams = number of moles * molar mass = 0.165 mol * (2 * 16g/mol)

mass = 5.28 g ≈ 5.3 g

Answer: 5.3 g

3 0

3 years ago

Read 2 more answers

Before applying the corkscrew, Lucas discovers a bit of mold on the cork of a bottle of Pinot Noir. Lucas should A. ignore the m

Alenkinab [10]

The question says,'before applying the corkscrew, Lucas discovers a bit of mold on the cork of a bottle of Pinot Noir. Lucas should............. The correct option is B. The standard method of removing mold from wine cork is to dampen a clean napkin with water and use it to wipe the mold away from the cork. The cork should then be removed and the outside and the inside of the wine neck must be cleaned thoroughly as well.

3 0

2 years ago

The heat required to raise the temperature of 12g of water from 16 C to 21 C is:

NemiM [27]

Answer:

The heat required to raise the temperature of 12g of water from 16 C to 21 C is 60 cal.

Explanation:

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

There is a direct proportional relationship between heat and temperature. The constant of proportionality depends on the substance that constitutes the body as on its mass, and is the product of the specific heat by the mass of the body. So, the equation that allows calculating heat exchanges is:

Q = c * m * ΔT

where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

In this case, you know:

Q=?
c= 4.186 $\frac{J}{g*C}$
m= 12 g
ΔT=Tfinal - Tinitial= 21 °C - 16°C= 5 °C

Replacing:

Q= 4.186 $\frac{J}{g*C}$ *12 g *5 °C

Solving:

Q=251.16 J

Since 1 J is equal to 0.2388 cal, then the following rule of three can be applied: if 1 J is equal to 0.2388 cal, then 251.16 J to how many cal are?

$cal=\frac{251.16 J * 0.2388 cal}{1 J}$

cal= 59.98 ≅ 60

The heat required to raise the temperature of 12g of water from 16 C to 21 C is 60 cal.

3 0

2 years ago