Answer:
(a) 13.7 g.
(b) 28.91 g.
Explanation:
- molality (m) is the no. of moles of solute dissolved in 1.0 kg of solvent.
∴ m = (no. of moles of solute)/(mass of water (kg))
<em>∴ m = (mass/molar mass of solute)/(mass of water (kg)).</em>
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<u><em>(a) Calculate the mass of CaCl₂·6H₂O needed to prepare 0.125 m CaCl₂(aq) by using 500. g of water.</em></u>
∵ m = (mass/molar mass of CaCl₂·6H₂O)/(mass of water (kg)).
m = 0.125 m, molar mass of CaCl₂·6H₂O = 219.0757 g/mol, mass of water = 500.0 g = 0.5 kg.
∴ 0.125 m = (mass of CaCl₂·6H₂O / 219.0757 g/mol)/(0.5 kg).
∴ mass of CaCl₂·6H₂O = (0.125 m)(219.0757 g/mol)(0.5 kg) = 13.7 g.
<u><em>(b) What mass of NiSO₄·6H₂O must be dissolved in 500. g of water to produce 0.22 m NiSO₄(aq)?</em></u>
∵ m = (mass/molar mass of NiSO₄·6H₂O)/(mass of water (kg)).
m = 0.22 m, molar mass of NiSO₄·6H₂O = 262.84 g/mol, mass of water = 500.0 g = 0.5 kg.
∴ 0.125 m = (mass of NiSO₄·6H₂O / 262.84 g/mol)/(0.5 kg).
∴ mass of NiSO₄·6H₂O = (0.22 m)(262.84 g/mol)(0.5 kg) = 28.91 g.
Answer:
C. If Assertion is true statement but Reason is false.
Explanation:
The burning of magnesium in air produces magnesium oxide as shown by the equation;
2Mg(s) + O2(g) -----> 2MgO(s)
The magnesium oxide solid is recovered as a white ash. This is a typical example of an oxidation reaction which is also a combustion reaction.
The reason has nothing at all to do with the assertion hence the answer given.
Magnesium oxide is basic just like the oxides of other metals and dissolves in water to yield an alkali.
Calculando a massa molar (molar peso) Para Calcular a massa molar de hum Composto químico, ponha SUA fórmula E clique em 'Calcular'. Na Fórmula química that rápido Você PODE USAR: <span>QUALQUÉR elemento químico Grupos Funcionais: D, Ph, Me, Et, Bu, AcAc, Para, Ts, Tos, Bz, TMS, tBu, Bzl, Bn, Dmg PARENTESIS () UO colchetes [] . Nomes Comuns de Compostos. </span><span>Os Exemplos de Cálculos de Massa molar: </span> NaCl <span>, </span> o Ca (OH) 2 <span>, </span> K4 [Fe (CN) 6] <span>, </span> CuSO4 * 5H2O <span>, </span> água <span>, </span> ácido nítrico <span>, </span> permanganato de potássio <span>, </span> etanol <span>, </span> frutose . Peso Computação molecular (massa molecular) para calcular o peso molecular de um composto químico entrar em sua fórmula, especifique seu número de massa isotópica depois de cada elemento entre colchetes. <span>Os Exemplos de Cálculos de peso molecular:</span> C [14] o [16] 2 <span>,</span> S [34] O [16] 2 <span>.</span> Definição de massa molecular, o peso molecular, uma massa molar e do peso molar <span><span><span>Massa molecular</span></span></span><span><span> ( </span></span><span><span><span>peso molecular</span></span></span><span><span> ) e uma massa de uma molécula de uma substancia e e Expressa nsa unificadas unidades de massa atómica (u). </span></span><span><span>(1 u E igual a 1/12 da massa de hum átomo de carbono-12) </span></span><span><span><span>Massa Molar</span></span></span><span><span> ( </span></span><span><span><span>molar peso</span></span></span><span><span> ) E uma massa de Uma toupeira de Uma substancia ê ê expresso em g / mol.</span></span><span> Pesos dos Átomos e isótopos São de </span><span>NIST Artigo </span><span>.</span> DEIXE Seu comentário <span>Sobre a SUA Experiência com uma calculadora de Peso Molecular </span><span>Pesos </span><span>moleculares de Aminoacidos: Relacionados</span>
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A cold air mass moves into an area of warm air
Answer:
8.73
Explanation:
when you are adding or subtracting numbers, the sigfig (significant figure) is based on how many numbers after the decimal. with this info, we can see that 15.67 has 2 sigfigs and 6.943 has 3 sigfigs. when you subtract normally, you would get 8.727, which has 3 sigfigs, so you would round the last 7 up to get 8.73 with 2 sigfigs!
also it is to 2 sigfigs because we know that we go by the least number of sigfigs. hope this helped!
