#2 6th grade science

Which of the following is NOT an example of covalent bonding? * 2 points H20 NaF NH3 O2

Pachacha [2.7K]

Answer:

I THINK NH3

Explanation:

4 0

3 years ago

Complete the acid–base equation for the dissolution of the following compound into liquid HF solvent. The relevant pKa values ar

LenKa [72]

Answer:

The balanced chemical equation: NH₃ + 2 HF → NH₄⁺ + HF₂⁻

Explanation:

According to the Brønsted–Lowry acid–base theory, the acid- base reaction is a type of chemical reaction between the acid and base to give a conjugate acid and a conjugate base.

In this reaction, a Brønsted–Lowry acid loses a proton to form a conjugate base. Whereas, a Brønsted–Lowry base accepts a proton to form a conjugate acid.

Acid + Base ⇌ Conjugate Base + Conjugate Acid

The acid dissociation constant (Kₐ) signifies the acidic strength of a chemical species.

∵ pKₐ = - log Kₐ

Thus for a strong acid, Kₐ value is large and pKₐ value is small.

pKₐ (HF) = 3.2 → strong acid

pKₐ (NH₃) = 38 → weak acid

The chemical reaction involved in the dissolution process:

NH₃ + 2 HF → NH₄⁺ + HF₂⁻

In this acid-base reaction, the acid HF reacts with NH₃ base to give the conjugate base HF₂⁻ and conjugate acid NH₄⁺.

HF (acid) donates a proton to form the conjugate base, HF₂⁻ ion. NH₃ (base) accepts a proton to form the conjugate acid.

7 0

3 years ago

A 133.8-gram sample of bronze was 10.3% tin by mass. Determine the total mass of tin in the sample.

Kay [80]

You just need to multiply the total mass by the decimal value of the part that is tin. 133.8*0.103=13.8g (following the rules of significant figures).

6 0

3 years ago

a sample of compound determined to contain 1.71 g C and 0.287 g H. The corresponding empirical formula is

fiasKO [112]

Answer: The empirical formula is $CH_2$ .

Explanation:

Mass of C = 1.71 g

Mass of H = 0.287 g

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{1.71g}{12g/mole}=0.142moles$

Moles of H = $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{0.287g}{1g/mole}=0.287moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{0.142}{0.142}=1$

For H = $\frac{0.287}{0.142}=2$

The ratio of C: H = 1: 2

Hence the empirical formula is $CH_2$ .

4 0

3 years ago

Why was the line of best fit method used to determine the experimental value of absolute zero?

BartSMP [9]

Answer:

Because the x-intercet of the graph represents volume zero, which indicates the minimum possible temperature or absolute zero.

Explanation:

Charle's Law for ideal gases states that, at constant pressure, the temperature and the volume of a sample of gas are protortional.

$\dfrac{V}{T}=k\\\\V=kT$

That means that the graph of the relationship between Temperature, in Kelivn, and Volume is a line, which passes through the origin.

When you work with Temperature in Celsius, and the temperature is placed on the x-axis, the line is shifted to the left 273.15ºC.

Meaning that the Volume at 273.15ºC is zero.

You cannot reach such low temperatures in an experiment, and also, volume zero is not real.

Nevertheless, you can draw the line of best fit and extend it until the x-axis (corresponding to a theoretical volume equal to zero), and read the corresponding temperature.

Subject to the experimental errors, and the fact that the real gases are not ideal, the temperature that you read on the x-axis is the minimum possible temperature (absolute zero) as the minimum possible volume is zero.

3 0

3 years ago