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3 years ago

What is the SI unit of mass

Chemistry

2 answers:

Alex Ar [27]3 years ago

6 0

Answer: Kilogram (kg)

Explanation: The SI unit of mass is the kilogram (kg). It is equal to the mass of the international prototype of the kilogram and it is defined as the mass of platinum-iridum (Pt-Ir).

FinnZ [79.3K]3 years ago

4 0

Answer:

kg or kilograms

Explanation:

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How many atoms are in a sample of 72.8 grams calcium ?

MArishka [77]

First find the moles
moles of the calcium= 72.8 / 40
moles of calcium in 72.8g = 1.82mol

number of atoms= moles x Avogadro constant
atoms = 1.82 x 6.02x10+23
so the number of atoms is 1.096x10+24

6 0

3 years ago

30,000 J of heat are added to 23.0 kg of steel to reach a final temperature of 140

kolbaska11 [484]

The initial temperature is 137.34 °C.

<u>Explanation:</u>

As the specific heat formula says that the heat energy required is directly proportional to the mass and change in temperature of the system.

Q = mcΔT

So, here the mass m is given as 23 kg, the specific heat of steel is given as c = 490 J/kg°C and the initial temperature is required to find with the final temperature being 140 °C. Also the heat energy required is 30,000 J.

ΔT = $\frac{Q}{mc}$

ΔT = $\frac{30000}{23 \times 490} = \frac{30000}{11270} =2.66$

Since the difference in temperature is 2.66, then the initial temperature will be

Final temperature - Initial temperature = Change in temperature

140-Initial temperature = 2.66

Initial temperature = 140-2.66 = 137.34 °C

Thus, the initial temperature is 137.34 °C.

7 0

3 years ago

To create a program with block-based code, the programmer needs to drag the blocks of code into the _____.

padilas [110]

Editor. That’s where you make the code

8 0

2 years ago

The first strings of holiday lights were manufactured as series circuits. Which explains why this method is no longer used? A. I

user100 [1]

B because once the circuit is burned the lights will all go of

3 0

2 years ago

Iron is biologically important in the transport of oxygen by red blood cells from the lungs to the various organs of the body. I

Aneli [31]

Answer : The number of iron atoms present in each red blood cell are, $1.077\times 10^9$

Explanation :

First we have to calculate the moles of iron.

$\text{Moles of iron}=\frac{\text{Mass of iron}}{\text{Molar mass of iron}}=\frac{2.90g}{55.85g/mole}=0.0519moles$

Now we have to calculate the number of iron atoms.

As, 1 mole of iron contains $6.022\times 10^{23}$ number of iron atoms

So, 0.0519 mole of iron contains $0.0519\times 6.022\times 10^{23}=3.125\times 10^{22}$ number of iron atoms

Now we have to calculate the number of iron atoms are present in each red blood cell.

Number of iron atoms are present in each red blood cell = $\frac{\text{Number of iron atoms}}{\text{Total number of red blood cells}}$

Number of iron atoms are present in each red blood cell = $\frac{3.125\times 10^{22}}{2.90\times 10^{13}}$

Number of iron atoms are present in each red blood cell = $1.077\times 10^9$

Therefore, the number of iron atoms present in each red blood cell are, $1.077\times 10^9$

6 0

2 years ago