ASAP PLZ HELP CHEMISTRY!!! CALCULATE THE MEAN AND THE UNCERTAINTY FOR EACH EXPERIMENT!!!

Chemistry

1 answer:

STALIN [3.7K]4 years ago

3 0

Answer:

MEANS:

1 = 97.7

2 = 74.3

3 = 50

4 = 30

5 = 13

UNCERTAINTY:

gimme a sec, ill put it in the comments under this

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Calculate the amount in grams of Na2CO3 needed to react with HCL to produce 120g NaCl

worty [1.4K]

Let's start off with the balanced chemical equation:

$Na_2CO_{3_{(s)}} + \textbf2HCl_{_{(aq)}}\rightarrow CO_{2_{(g)}} + H_2O_{_{(l)}} + \textbf2NaCl_{_{(aq)}}$

Assuming the sodium carbonate is the limiting reagent, look at the coefficients of sodium carbonate and sodium chloride and use those as a ratio of sodium carbonate to sodium chloride: 1:2.

Since you have the required mass of NaCl, convert this to moles.

Assuming you know how to find the molar mass of NaCl:

$M_{NaCl} = 58.44g/mol$
$n = \frac{m}{M}$
$n_{NaCl} = \frac{120g}{58.44g/mol}$
$n_{NaCl} = 2.053mol$

Using the ratio, since 1 mole of sodium carbonate is required to produce 2 moles of sodium chloride, cross-multiply the ratios:

$1:2 = x:2.053mol$
$2x = 2.053mol$
$x = 1.027mol$

Therefore 1.027 moles of sodium carbonate is required to produce the required amount of sodium chloride. Convert to mass for your final answer:

$n_{Na_2CO_3} = 1.027mol$
$M_{Na_2CO_3} = 105.99g/mol$
$m = nM$
$m = (1.027mol)(105.99g/mol)$
$m_{Na_2CO_3} = 108.85g$

Hope this helps :)

6 0

3 years ago

Describe at least two ways that a researcher can minimize experimental errors in an investigation

snow_tiger [21]

Experimental errors occurs in the execution of experiment design. Example of experimental errors are mistakes in data entry, systematic error, and random error caused by environmental conditions. Did you even heard about type I and type II error? Because that may be the 2 ways you are looking for.
A false positive is called a Type I error, and it is the type of error that incorrectly rejecting the null hypothesis in the favor of the alternatives.
A false negative is what you called Type II error, it is the opposite of type I error and it is the false acceptance of the null hypothesis. A type II errors are not seen to be as problematic as type I error, type I error is more serious than type II error, because you have wrongly rejected the null hypothesis.

5 0

3 years ago

Zinc is used as a coating for steel to protect the steel from environmental corrosion. If a piece of steel is submerged in an el

sweet [91]

Answer:

A) 3.17 g of Zn

Explanation:

Let's consider the reduction of Zn(II) that occurs in an electrolysis bath.

Zn⁺²(aq) + 2e⁻ → Zn(s)

We can establish the following relations:

1 min = 60 s
1 A = 1 C/s
The charge of 1 mole of electrons is 96,468 C (Faraday's constant).
When 2 moles of electrons circulate, 1 mole of Zn is deposited.
The molar mass of Zn is 65.38 g/mol

The mass of Zn deposited under these conditions is:

$24min \times \frac{60s}{1min} \times \frac{6.5C}{s} \times \frac{1mol\ e^{-} }{96,468C} \times \frac{1molZn}{2mol\ e^{-}} \times \frac{65.38g}{1molZn} = 3.17 g$