Question

硼有兩種同位素¹⁰B和¹¹B，硼元素的近似相對(duì)原子質(zhì)量為10.8，則¹⁰B的質(zhì)量分?jǐn)?shù)為

 

．

Answer 1

分析：硼元素的相對(duì)原子質(zhì)量是10.8，則硼元素的摩爾質(zhì)量是10.8g/mol，再根據(jù)

.

M

=

m

n

計(jì)算其物質(zhì)的量之比，再根據(jù)物質(zhì)的量計(jì)算其質(zhì)量分?jǐn)?shù)．

解答：解：硼元素的相對(duì)原子質(zhì)量是10.8，則硼元素的摩爾質(zhì)量是10.8g/mol，
設(shè)¹⁰B和¹¹B的物質(zhì)的量分別是xmol、ymol，則

.

M

=

10g/mol×xmol+11g/mol×ymol

(x+y)mol

=10.8g/mol，x：y=1：4，設(shè)¹⁰B和¹¹B的物質(zhì)的量分別是1mol、4mol，
則¹⁰B的質(zhì)量分?jǐn)?shù)=

10g/mol×1mol

10g/mol×1mol+11g/mol×4mol

×100%=18.5%，
故答案為：18.5%．

點(diǎn)評(píng)：本題考查了物質(zhì)的量的計(jì)算，正確理解平均摩爾質(zhì)量的計(jì)算方法是解本題關(guān)鍵，再結(jié)合質(zhì)量分?jǐn)?shù)公式進(jìn)行解答，題目難度不大．