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3 years ago

This is my first question on Brainly, Can someone explain Molar mass to me? I am not very good with it..

1 answer:

5 0

Hey,
A mole is a unit of measure that helps us compare particles of any given substance and its mass. ... The molar mass, also known as molecular weight, is the sum of the total mass in grams of all the atoms that make up a mole of a particular molecule. The unit used to measure is grams per mole.

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which caused a change in matter. Select each procedure that is likely a chemical change. Salt crystals were crushed into a fine

olga55 [171]

Procedures that are likely a chemical change are:

- Bubbles were produced when iron was placed in acid.

- Two liquids were combined, and a solid appeared

- A white substance turned blue when water was added.

5 0

2 years ago

Read 2 more answers

One of the radioactive isotopes used in medical treatment or analysis is chromium-51. The half-life of chromium-51 is 28 days. H

Goryan [66]

Answer : The time required for decay is, 84 days.

Explanation :

Half-life of chromium-51 = 28 days

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{28\text{ days}}$

$k=0.0248\text{ days}^{-1}$

Now we have to calculate the time required for decay.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant

t = time taken by sample = ?

a = let initial activity of the sample = 100

a - x = amount left after decay process = 12.5

Now put all the given values in above equation, we get

$t=\frac{2.303}{0.0248}\log\frac{100}{12.5}$

$t=83.9\text{ days}\approx 84\text{ days}$

Therefore, the time required for decay is, 84 days.

7 0

3 years ago

A quantity of 0.225 g of a metal M (molar mass = 27.0 g/mol) liberated 0.303 L of molecular hydrogen (measured at 17°C and 741 m

Lana71 [14]

Answer:

Oxide of M is $M_2O_3$ and sulfate of $M_2(SO_4)_3$

Explanation:

0.303 L of molecular hydrogen gas measured at 17°C and 741 mmHg.

Let moles of hydrogen gas be n.

Temperature of the gas ,T= 17°C =290 K

Pressure of the gas ,P= 741 mmHg= 0.9633 atm

Volume occupied by gas , V = 0.303 L

Using an ideal gas equation:

$PV=nRT$

$n=\frac{PV}{RT}=\frac{0.9633 atm\times 0.303 L}{0.0821 atm L/mol K\times 290 K}=0.01225 mol$

Moles of hydrogen gas produced = 0.01225 mol

$2M+2xHCl\rightarrow 2MCl_x+xH_2$

Moles of metal = $\frac{0.225 g}{27.0 g/mol}=8.3333 mol$

So, 8.3333 mol of metal M gives 0.01225 mol of hydrogen gas.

$\frac{8.3333}{0.01225 mol}=\frac{2}{x}$

x = 2.9 ≈ 3

$2M+6HCl\rightarrow 2MCl_3+3H_2$

$MCl_3\rightarrow M^{3+}+Cl^-$

Formulas for the oxide and sulfate of M will be:

Oxide of M is $M_2O_3$ and sulfate of $M_2(SO_4)_3$ .

3 0

3 years ago

What kinds of substances besides water can be involved in hydrogen bonding?

MrMuchimi

<span>Kind of substance besides water:
The best example of hydrogen bonding excluding water is DNA. The two strands of polymers are connected by hydrogen bonds between the nucleotide bases</span>.

7 0

3 years ago

Fireworks change (blank) into (blank) and (blank) energy.

Nitella [24]

Fireworks changes chemical energy into light energy

5 0

3 years ago