Which are the MOST LIKELY products of the reaction between sodium metal and chlorine gas?

Calculate the number of atoms in 2.5 moles of Si.

Ede4ka [16]

Answer:

$\boxed {\boxed {\sf About \ 1.5 * 10^{24} \ atoms \ Si}}$

Explanation:

When converting from moles to atoms, we must use Avogadro's number. This number tells us there are 6.022 * 10²³ atoms in 1 mole. We can multiply this number by the number of moles.

First, we must set up Avogadro's number as a ratio.

$\frac {6.022 \ * 10^{23} \ atoms \ Si }{1 \ mol \ Si}}$

Next, multiply the number of moles by the ratio.

$2.5 \ mol \ Si *\frac {6.022 \ * 10^{23} \ atoms \ Si }{1 \ mol \ Si}}$

When we multiply, the moles of silicon will cancel.

$2.5 * \frac {6.022 \ * 10^{23} \ atoms \ Si }{1}}$

Since the denominator of the fraction is 1, we can cancel it out too.

$2.5 * {6.022 \ * 10^{23} \ atoms \ Si }$

$1.5055 * 10^{24} \ atoms \ Si$

The original measurement (2.5 moles) has 2 significant figures (2 and 5). Therefore we must round to 2 sig figs. For this question, 2 sig figs is the tenth place.

The 0 in the hundredth place tells us to leave the 5 in the tenth place.

$1.5 * 10^{24} \ atoms \ Si$

There are about <u>1.5 * 10²⁴ atoms of silicon.</u>

7 0

3 years ago

What elements make up the formula: H2SO4

Delvig [45]

Hydrogen, sulphur, oxygen

8 0

4 years ago

Describe how the law of conservation of energy relates to 2 types of energy. Include an example.

Sever21 [200]

Answer:

Explanation:

The law of conservation of energy states that energy is neither created or destroyed but transformed from one form to another for example radio transmitter convert electrical energy to sound energy, water from one height to a lower height convert gravitational potential energy to kinetic energy.

8 0

4 years ago

A small amount of liquid bromine is added to a container which is then sealed.

LiRa [457]

Br2(i) would be sealed due to my calculations

5 0

3 years ago

To do an experiment with the peptide H-A-P-P-Y you need to make two buffers. One where the peptide has a net negative charge (Bu

nata0808 [166]

Answer:

Buffer A: pH 5.25; 2.82 mol of acetate for every 1 mol of acetic acid

Buffer B: pH 9.25; 11.2 mol of bicarbonate for every 1 mol of carbonate

Explanation:

The pI of a protein is the pH at which it has a net charge of zero.

The protein has a positive charge below the pI and a negative charge above it.

Since pI = 7.25, let's make one buffer at pH = 5.25 and one at pH 9.25.

1. Preparation of pH 5.25 buffer

(a) Choose the conjugate pair

We should choose a buffer with pKₐ close to 5.25.

Acetic acid has pKₐ = 4.8, so let's make acetate buffer.

(b) Protocol for preparation

We can use the Henderson-Hasselbalch equation to get the acid/base ratio.

$\begin{array}{rcl}\text{pH} & = & \text{pK}_{\text{a}} + \log \left(\dfrac{[\text{A}^{-}]}{\text{[HA]}}\right )\\\\5.25& = & 4.8 +\log \left(\dfrac{[\text{A}^{-}]}{\text{[HA]}}\right )\\\\0.45& = & \log \left(\dfrac{[\text{A}^{-}]}{\text{[HA]}}\right )\\\\2.82 & = &\dfrac{[\text{A}^{-}]}{\text{[HA]}}\\\\\end{array}\\\text{The base/acid ratio must be $\mathbf{2.82:1}$}$

To make the buffer, mix the solutions to get a ratio of 2.82 mol of acetate for every 1 mol of acetic acid.

2. Preparation of pH 9.25 buffer

(a) Choose the conjugate pair

We should choose a buffer with pKₐ close to 9.25.

Bicarbonate has pKₐ = 10.3, so let's make a pH 9.25 bicarbonate buffer.

(b) Protocol for preparation

$\begin{array}{rcl}\text{pH} & = & \text{pK}_{\text{a}} + \log \left(\dfrac{[\text{A}^{-}]}{\text{[HA]}}\right )\\\\9.25& = & 10.3 +\log \left(\dfrac{[\text{A}^{-}]}{\text{[HA]}}\right )\\\\-1.05& = & \log \left(\dfrac{[\text{A}^{-}]}{\text{[HA]}}\right )\\\\0.08913& = &\dfrac{[\text{A}^{-}]}{\text{[HA]}}\\\\\dfrac{1}{11.2}& = &\dfrac{[\text{A}^{-}]}{\text{[HA]}}\\\\\end{array}\\\text{The acid/base ratio must be $\mathbf{11.2:1}$}$

To make the buffer, mix the solutions to get a ratio of 11.2 mol of bicarbonate for every 1 mol of carbonate.

3 0

3 years ago