If the half-life of a radioisotope is 250 years how much of a 96.0 gram sample will remain after 750 years

A sample that contains aluminum is reacted with sulfuric acid according to the equation given below. When the aluminum dissolves

GrogVix [38]

Answer:

$m_{H_2}=0.0574gH_2$

Explanation:

Hello,

In this case, the information about the pressure, volume and temperature are enough to compute the mass of hydrogen assuming its ideal behavior:

$n_{H_2}=\frac{PV}{RT}=\frac{739mmHg*\frac{1atm}{760mmHg}*0.722 L}{0.082 \frac{atm*L}{mol*K}*298.15K} =0.0287molH_2$

The mass is:

$m_{H_2}=0.0287molH_2*\frac{2gH_2}{1molH_2} \\m_{H_2}=0.0574gH_2$

Best regards.

5 0

3 years ago

hat range, give the lower value and the higher value, respectively, for the following. (a) How many cubic meters of water are in

torisob [31]

Answer:

a) 9424797000 m3

b) 9424797000000 liters

c) 9424797000000 kg

Explanation

Cylinder has a radius of 1 km= 1000 m.

Area Cylinder = π r^2 = 3,141599* (1000m)^2 = 3141599 m2

a) Volume Cylinder= area x Height=3141599 m2* 3000 m= 9424797000 m3

b) 1000 liters= 1m3, 9424797000 * 1000 = 9424797000000 liters

c) densiy = 1000 kg/m3, or 1 kg/ liter, mass= 9424797000 lt * 1kg/lt =

9424797000 kg

5 0

3 years ago

How would you prepare 250 mL of a 0.100 M solution of fluoride ions from solid CaF2?

andrey2020 [161]

In 250 mL of volumetric flask add 0.975875 grams of $CaF_2$ and dissolve it in the 250 mL of water.

Given:

The solid of calcium fluoride.

To prepare:

The 250 mL solution of 0.100 M of fluoride ions from solid calcium fluoride.

Method:

Molarity of the fluoride ion solution needed = M = 0.100 M

The volume of the fluoride ion solution needed = V = 250 mL

$1 mL = 0.001L\\V=250 mL=250\times 0.001 L=0.250 L$

The moles of fluoride ion needed = n

According to the definition of molarity:

$M=\frac{n}{V}\\0.100M=\frac{n}{0.250 L}\\n=0.100M\times 0.250 L=0.025 mol$

Moles of fluoride ion = 0.025 mol

We know that solid calcium fluoride dissolves in water to give calcium ions and fluoride ions.

$CaF_2(s)\rightarrow Ca^{2+}(aq)+2F^-(aq)$

According to reaction, 2 moles of fluoride ions are obtained from 1 mole of calcium fluoride, then 0.025 moles of fluoride ions will be obtained from:

$=\frac{1}{2}\times 0.025 mol=0.0125 \text{mol of } CaF_2$

Moles of calcium fluoride = 0.0125 mol

Mass of calcium fluoride needed to prepare the solution :

$=0.0125 mol\times 78.07 g/mol=0.975875 g$

Preparation:

Weight 0.975875 grams of calcium fluoride
Add weighed calcium fluoride to a volumetric flask of the labeled volume of 250 mL.
Now add a small amount of water to dissolve the calcium fluoride completely.
After this add more water up to the mark of the volumetric flask of volume 250 mL.

Learn more about molarity of solution ere:

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3 0

3 years ago

Which postmortem parameter is fixed by 8 hours?

lara [203]

Answer:

Algor mortis is the change which is an immediately sign of death. It involves the cooling of body. The body temperature decreases as the body after death looses the control over the circulation and exchange of gases and the control over the homeostasis. The temperature decreases until the body attains equilibrium with the external environmental temperature. The postmortem cooling or algor mortis gets fixed by 8- 10 hours after death. The temperature of the body after death can be used to determine the time since death. This can be measured by determining the temperature of the rectum which is proved to be most accurate or any other orifice such as nasal, ear and vaginal can also be used.

4 0

3 years ago

True or False? Weak bases dissociate completely into (OH)- and metal cations.

ki77a [65]

Answer:

False

Explanation:

When weak bases dissociate, an equilibrium is established rather than dissociating 100%. So OH- and metal ions are partially ionized.

7 0

3 years ago