Please help i need to do good in this class

When an athlete gets hurt they apply sometimes an instant cold pack to the injury. The instant cold pack works by mixing two che

NeX [460]

Answer:

The evidence showing that there is a chemical reaction taking place is the instantaneous temperature drop once the cold pack is shaken.

Explanation:

When an athlete applies a cold pack to the injury, they shake it before, mixing the water and <em>ammonium-nitrate fertilizer</em> inside the cold pack. This mixing is an endothermic reaction, which means it absorbs heat. In turn, the temperature falls to 35 F for around 10 minutes.

3 0

2 years ago

Calculate the specific heat capacity for a 22.7-g sample of lead that absorbs 237 J when its temperature increases from 29.8 °C

soldier1979 [14.2K]

Answer:

$\boxed {\boxed {\sf c\approx 0.159 \ J/ g \textdegree C}}$

Explanation:

We are asked to find the specific heat capacity of a sample of lead. The formula for calculating the specific heat capacity is:

$c= \frac{Q}{m \times \Delta T}$

The heat absorbed (Q) is 237 Joules. The mass of the lead sample (m) is 22.7 grams. The change in temperature (ΔT) is the difference between the final temperature and the initial temperature. The temperature increases <em>from</em> 29.8 °C <em>to </em>95.6 °C.

ΔT = final temperature -inital temperature
ΔT= 95.6 °C - 29.8 °C = 65.8 °C

Now we know all three variables and can substitute them into the formula.

Q= 237 J
m= 22.7 g
ΔT = 65.8 °C

$c= \frac {237 \ J}{22.7 \ g \ \times \ 65.8 \textdegree C}$

Solve the denominator.

22.7 g * 65.8 °C = 1493.66 g °C

$c= \frac {237 \ J}{1493.66 \ g \textdegree C}$

Divide.

$c= 0.1586706479 J /g \textdegree C$

The original values of heat, temperature, and mass all have 3 significant figures, so our answer must have the same. For the number we found that is the thousandth place. The 6 in the ten-thousandth place tells us to round the 8 up to a 9.

$c \approx 0.159 \ J/g \textdegree C$

The specific heat capacity of lead is approximately <u>0.159 Joules per gram degree Celsius.</u>

3 0

1 year ago

This stadium can hold 100,000, or 1 x 105, people. The number of atoms in a grain of iron is about 1 x 1018. Would you need 1 x

nata0808 [166]

<h3>Answer:</h3>

1 x 10^13 stadiums

<h3>Explanation:</h3>

We are given that;

1 stadium holds = 1 × 10^5 people

Number of iron atoms is 1 × 10^18 atoms

Assuming the stadium would carry an equivalent number of atoms as people.

Then, 1 stadium will carry 1 × 10^5 atoms

Therefore,

To calculate the number of stadiums that can hold 1 × 10^18 atoms we divide the total number of atoms by the number of atoms per stadium.

Number of stadiums = Total number of atoms ÷ Number of atoms per stadium

= 1 × 10^18 atoms ÷ 1 × 10^5 atoms/stadium

= 1 × 10^13 Stadiums

Thus, 1 × 10^18 atoms would occupy 1 × 10^13 stadiums

7 0

1 year ago

If 3.18 x 10^23 atoms of iron react with 67.2 L of chlorine gas at STP, what is the maximum

spin [16.1K]

84.34 grams of grams of iron (III) chloride that can be produced is maximum because Fe is the limiting reagent in this reaction and chlorine gas is excess reagent.

Explanation:

Balanced chemical equation:

2 Fe + 3 Cl2 → 2 FeCl3

DATA GIVEN:

iron = atoms

mass of chlorine gas = 67.2 liters

mass of FeCl3 = ?

number of moles of iron will be calculated as

number of moles = $\frac{total number of atoms}{Avagaro's number}$